Dr. Edwin H. Land, who died March 1, 1991, at the age of 81, was the inventor of Polaroid film which develops itself right after the picture is taken. According to the Associated Press story in the Champaign-Urbana News Gazette, 3-2-91, more than fifty years ago, Edwin Land took a picture of his 3-year-old daughter, who asked to see it. He told her that she wouldn't be able to see it until it was developed. When she asked, "Why not?" he thought very hard for about an hour and came up with an idea of how to make Polaroid film. Dr. Land dropped out of Harvard before graduating to work on inventions, and eventually had 537 patents. He founded the Polaroid Corporation, whose president, 1. MacAllister Booth, said, "He taught us new science, new industry and a new way of working, which together continue to form the very foundation of Polaroid Corporation." Only Thomas Edison collected more patents for inventions.

    According to "Week-end Edition" of National Public Radio, Dr. Land was said to have "a ferocious intensity of concentration on the object of the moment." When he was asked to describe himself, Dr. Land said, "I am first of all an artistic person, with love, affection, and sharing, making beauty a pan of everyday life." He was very unusual in shutting out all other things to concentrate on just one thing. He was said to have "a spiritual quality to insist that impossible things can happen." Dr Land : s most famous for inventing the Polaroid Camera. He invented instant Xrays, Polaroid sunglasses, a 3-D movie projector and anti-glare goggles for dogs. Dr. Land was a member of the President's Science Advisory Committee, and served on many other government and civic bodies.-JE
       I like the way Dr. Land describes his method of inquiry. I nominate Edwin Land as a posthumous member of the SNN Serendipitous Club! (By the way, Polaroid offers cameras to teachers through the Polaroid Educational Program. Teachers can obtain a camera and curriculum materials from Polaroid by attending a two hour workshop for $7.00. Fifty teachers must participate in the training to get this offer. Extra cameras for students can be obtained when you buy film. If you are interested, you can contact me for the details.)-MO
 

    Did you know that plants have diseases just like you do? There are many interesting plant diseases and some have changed human history. Have your parents tell you about the huge American Elm trees that used to shade our cities. They were killed by Dutch Elm Disease in the 1960's before you were born! Potato Late Blight caused a famine in Ireland that forced many Irish to migrate to the United States in the 1 800's.

    Phytopathologists are plant doctors. Phytopathology or Plant Pathology is the study of plant diseases and how to control them. Plant diseases are caused by some of the same types of microorganisms that affect you and me. Plants have bacterial diseases just like you have pneumonia, sore throats and boils caused by bacteria; they have fungal diseases just like you have athlete's foot [caused by a fungus], and they have viral diseases just like you have measles, flu, colds or chicken pox caused by different viruses. The first virus to be purified and studied was a plant virus, Tobacco mosaic virus [TMV]! Wendel Stanley got a Nobel Prize for this work, [Plant viruses are given names which indicate their host and the most conspicuous symptoms of the disease they cause]. TMV causes tobacco plants to develop a patchy green color or mosaic. In that vein, how about human red spots virus?

    Plants can be protected from some diseases by a process similar to your small pox or whooping cough vaccination. You are protected from small pox by a prior inoculation with the cow pox virus, which is related to small pox virus. Louis Pasteur discovered this protection and demonstrated it on his own children! You don't get cow pox even though you are given the virus, and this protects you from the serious disease caused by the small pox virus! Inoculating plants with weakened or related microorganisms can protect them from diseases too.
Plants also have ways of protecting themselves from diseases by producing antibiotics which phytopathologists call phytoalexins. These 'plant warding-off compounds' prevent microorganisms from growing on them in much the same way that penicillin protects you or helps you get well faster.

    Did you know that plants produce their own aspirin? Recent reports in Science 250:1002-1005 indicate that plants produce salicylic acid [a close relative of aspirin] in response to infections by viruses and fungi. Indians used to chew on willow bark for a source of this compound when they were sick!

    This Spring look at the leaves of plants and your lawn for spots which tell you that plants have diseases too! -Jack Paxton

    For example, many children in first grade know that ten hundreds make a thousand, and it is not too hard to understand that a thousand thousands make a million. The way we write numbers makes this easy.

       1 x 10 = 10 or 101 One child has ten fingers.
     10 x 10 = 100 or 102 Ten children have a hundred fingers.
   100 x 10 = 1,000 or 103 A hundred children have a thousand fingers.
1,000 x 10 = 10,000 or 104 and so on.

    Any child who gets interested in this pattern (or the entire times ten table) can follow it and multiply any of the answers already obtained by ten. How many zeros would you need to write 100 x 100? So you can write the times tables for Ins, 100s, 1,000s, etc., just by counting zeros. (Of course, you can also just as easily multiply any number at all by these numbers.)

    Dividing is the inverse of multiplication, so that should be easy, too, if we stick to tens and multiples of tens.
100 + 10 = 10 That means that you can find ten tens (which is a very funny way of talking only found in mathematics) in a hundred fingers. To speak more naturally, that means just ten children are needed to have 100 fingers, the same thing as we said about multiplying 10 x 10.
Now, to divide. we subtract zeros instead of adding them, so you can write the answers to:

           10 + 10=?
         100+ 10 = ?
    1,000 + 10 = ?
  10,000 + 10 = ?
100,000 + 10 = ?
Etc.

10 + 10 = ? Well, 1 zero - 1 zero = 0 zeros, so the answer is just 1, with no zeros at all attached. The others are also easy. But what about these:

  1 + 10 = ?
1 + 100 = ?
10+ 100=?
Etc. ?

Can you subtract this: 1 zero - 2 zeros = ?

    If you have one zero and Billy takes away two of your zeros, that is hard.

    But if you have one candy and Billy has two candies, how many more candies do you have than Billy? You don't have more. You have one less than he has. So an answer to 1 zero - 2 zeros could be one less zero. That's like 1/10, 10/100, 100/1,000, etc. There's one less zero on top. So we could just use the first one (1/10 or 10-1 ) as an answer for all of them.

    Those are very interesting divisions, because we can't find any answers to them in the list of numbers we were working with for multiplication. You see, 10 x 100 is 1,000 (103), which is the same as 100 x 10. But 100 + 10 = 10, or 101, which is not the same thing as 10 + 100, or 10-1. By the way 10 x 1/10 = 101 x loll = 10° = 1 (just 1 with no zeros), and 13 = 1 x 1 x 1. Do they make sense? So what does 110 = ? And what does 1-1° = ?
One way to think about 10 + 100 is to think that you have to buy 100 pieces of candy for a big party, and you only have 10 dollars to spend. How much could you spend for each piece of candy?

 
    (Another way is to think about: How many 100 dollar bills could you get at the bank for one 10 dollar bill? You may have to be a very good banker to figure that one out.) One answer to the amount you can spend on each piece of candy is $.1 or $.10--one tenth of a dollar, or ten cents. One answer to the question about 100 dollar bills, is 1/10 of one hundred dollar bill, but I doubt if the bank will cut off 1/10 of one for you.

1 + 10 = 1/10 = .1 (10-1) One tenth of a dollar is one dime.
1 + 100 = 1/100 = .01 (10-2) One hundredth of a dollar is one cent (a penny).
1 + 1,000 = 1/1,000 = .001 (10-3) One thousandth of a dollar is one milt
I don't know the names of smaller fractions of a dollar. You might have to make them up, yourself.
Now, if you remember that dividing is just the inverse of multiplying, we can divide:

10+ 100=?
10+ 1,000=?

    Try this one again: How many ten dollar bills would it take to just have one dollar? Can you imagine if you had a ten dollar bill and wanted to give one dollar to each of ten people? How would you do it? Somebody might cut a ten dollar bill into ten pieces and give one little strip to each person. That might not make them very happy. What could they each do with that little strip? Would a bank give them a real dollar bill for it? Well, that reminds me. In this case we could get the bank to change the ten dollar bill for ten one dollar bills. So that answer really works: One tenth of a ten dollar bill is one dollar. So banks, and people, can sometimes divide a single bill into ten smaller pieces of money, a hundred smaller pieces, etc.

    What we are doing is to "make up" numbers as answers to problems that won't work by the usual way of dividing. Dividing works by subtracting zeros, if the numbers you have to divide both begin with a " 1 " and have nothing else but "0's" in them. But when you get a funny, negative number of zeros by subtracting more than you had, we used a fraction for an answer. That's the same way it works if you have one apple and want to divide it into two pieces--you get a fraction for an answer.

Puzzle: Why is it that, in mathematics, we say one divided by two (1 + 2 = 1/2) when we want to divide one thing into two parts? It is the same problem if we want to divide six apples into three parts. We say six divided by three. (6 + 3 = 2) We can get messed up using by and into because they seem to be going in opposite directions, for we also say, three goes into six two times, but we write that differently. In English, we can also say: "Two apples divided into four pieces makes half an apple in each piece," but then in mathematics we say t w o divided by four. (2 + 4 = 1/2 Two apples divided b y (???) four pieces equals half an apple each.) If someone would explain to me why we English speaking people talk in two such conflicting ways about division, I would appreciate it. --JE

    Last month's article stimulated quite a few comments. For instance, twenty-year old Christopher said that he also heard the extinction of the dinosaur was caused by an asteroid strike. However, he surmised that the dense clouds covering the earth after the strike lowered the temperature of the earth and therefore the body temperature of the cold blooded dinosaur. Because of this, he concluded, the male dinosaur was unable to produce sperm and therefore the species became extinct.

    Franklin Middle School sixth-grader, Brandon, shared an article about dinosaurs he read in the Champaign-Urbana News-Gazette. He says he read in the "Our Wonderful Earth" section of the comics that temperature of sperm determines the sex of the offspring. When the temperature of the earth changed, only one sex was reproduced.

    Brandon searched through his family's recycle bucket and found the article from "Our Fascinating Earth" called "When One Sex Prevails." It says, "Research reveals that during incubation of alligator eggs a temperature difference determines the hatchling's sex. Eggs kept at about 80 degrees F develop into females, 86 degrees F produces males. Some scientists suspect this may provide an explanation for the extinction of the dinosaurs. Climactic changes 65 million years go could have caused one sex to dominate. This would disrupt reproductive patterns, and result in mass extinction. "

    Try walking across the room rapidly to see how many seconds it takes by a sweep second hand. Now count floor tiles to figure out how far you walked. Divide the number of feet by the number of seconds.

    The fastest dinosaur tracks ever found are those of a biped (about the weight of a racehorse) that ran across Texas long ago. The speed turns out to be 12 meters per second (39 feet per second).  People can't run that fast.  Race horses are even faster, for they usually win a race at a speed of 15 to 17 meters per second.

    Try walking steadily across the floor and stepping on a bathroom scale as you walk past it. Have someone watch the scale to see if you press more than your body weight when you step on it. Now, do the same walking rapidly. Now, running. Which presses more? How much more? How much do you think the foot of a Tyrannosaurus Rex would press when it ran?

    "These estimates give the impression that although large dinosaurs walked slowly, most were capable of quite a quick run and none needed to live in water or to rely on buoyancy for support (like whales and porpoises). The evidence from footprints suggests that if we had been alive at the time (and had had the nerve), we could have strolled alongside a walking sauropod or tyrannosaur, keeping up with it without difficulty.... I think I am probably fast enough to out run a pursuing tyrannosaur, but, perhaps fortunately, I am unlikely to have to try." -R. McNeill Alexander in Scientific American, April, 1991, p. 136. See also his book, Dynamics of Dinosaurs and Other Extinct Giants. Columbia University Press, 1989, and a book by Tony Thulborn, Dinosaur Tracks. Chapman and Hall, 1990.

    Andrew Nolte, in Mrs. Hall's kindergarten class at Taft School in Kankakee would like to know: What does dinosaur skin look like? Jack Kresl would like to know, "Do dinosaurs have ears?" Marques Anderson would like to know "Where did dinosaurs live?"

    Jack Easley replies: These are three great questions. I've been reading up on dinosaurs in the University Library and learning a lot.

    You see, Andrew, whenever dinosaurs died millions of years ago, the skin and meat, and everything except the bones rotted. So no dinosaur skin was ever found. However, a few dinosaurs did leave us a print of their skin, when the mud they were lying in turned to stone before it could be smoothed over. Here is a picture of a rock that shows where a dinosaur was pressing its skin on the mud. One dinosaur, a relative of triceratops, had 2-inch bumps all over its skin. It looks like all the skin prints were made by thick leathery skins.

 
    You could make a kind of fossil of interesting skin of a leaf, by painting it with nail polish. After the polish is dry, peel it off and look at it with a hand lens to see the patterns.

    For Ankylusaurus, there is more information on how the skin looked, because Ankylosaurus had bony plates on its skin, even on its eyelids, and those plates were turned to stone and preserved. One thing we can't tell is what color the skin was. But some large animals are camouflaged to match the jungle or forest they live in, so we can try to guess. So some scientists think they were striped or blotched different shades of green and brown, line soldiers in the jungle.

    Here is a picture of the trees that the dinosaurs lived in. They are drawn standing up, but fossil trees and dinosaurs are usually lying down.

 
    As to Jack Kresl's ear question, dinosaurs are related to lizards and birds, and they have no outside ears, just an ear drum in the skin, and an inner ear. So we think dinosaurs didn't have outside ears like we do. Like the dinosaurs' skin, if they had outside ears, they would not make fossils unless they had bony plates or they happened to make a print in mud that turned to stone. There are some fossil castings of vegetarian dinosaur inner ears which suggest they could hear the carnivorous dinosaurs coming. (See C. McGowan, The Successful Dragons, 1983, pp. 70-71 and p. 135.)

    To answer Marque's question about where dinosaurs lived the map of the world in the time of the dinosaurs was quite different from what it is today. The continents have moved around slowly, and are still moving-- about one or two inches every year.  Here is one map that shows how some scientists think the continents were arranged, all connected together, at the time the dinosaurs lived. Fossils of dinosaurs have turned up all over, even in Antarctica, as a recent news bulletin reported. Of course, some dinosaurs ate plants and some ate meat, and with different sizes, they must have had different habits about where they went to sleep.

    For example the Wilson Petrels, sea birds that spend the months of November-March in the Antarctic, fly north in April up the coasts of South America and Central America, head out to the North Atlantic during the summer, and in September, they cross the Atlantic and go south along the coasts of Europe and Africa. From there they cross the Atlantic toward South America, fly down the coasts and get to Western  Antarctica, where they spend the winter months again. This is the same pattern as the winds usually blow.

    In Germany, some scientists took caged birds into a planetarium when it was time for them to By south and set the stars on the ceiling for the season when they should fly north. The released birds flew north according to the stars in the ceiling instead of according to the real month. Outside, where the stars were right, the birds flew south.--JE

The February, 1991, issue of Science
 Network News contained three errors we
have identified:

On page one, in the middle of column 2, part of a sentence was missing from our article about an asteroid strike causing the extinction of the dinosaur. It should have read:
"The new theory was developed by a Nobel Prize winner, Luis W. Alvarez, and his son, Walter Alvarez."

On page 7, in quoting lack Paxton, we should have said I-10 pictograms per kilogram per year instead of 10- 1 ° pictograms per kilogram per year

On page 8, the graph was missing the label for the vertical line at the right: It should have said " I part per million." like this:

Percentage of receptors involved for different strengths of dioxin in the blood.

 Director lack Easley
 Editor Michele Olsen