Chapter 16 The second part accidentally broke into Princeton-8

I had my own "laboratory" when I was very young.Of course, it's not a laboratory if you're measuring something or doing important experiments.Actually, I just stayed there and played around: I made my own motors, or I made gadgets out of photocells—like designing a little electronic gadget that would turn on another set of parts when something swung in front of the photocells, etc.; Also found some silicon chips to play with.In short, I was there to do what I wanted to do.Only when I was making lampholders did I do some calculations to see how to control the voltage with switches and bulbs; but these were only applications, and I haven't really done any great experiments.

I also have a microscope, and I am often obsessed with the world under the microscope; this also requires a lot of patience.I put things under the microscope and looked at them endlessly.Like everyone else, I saw many interesting things, like diatoms slowly swimming from one side of the glass sheet to the other...etc. One day, while observing paramecia, I came across something that was not mentioned in middle school or even college textbooks.I often feel that these textbooks smugly simplify the world."Paramecia are extremely simple creatures, and behavior is even more so. When they hit something else, they back off, turn around and start again," they said.

But it's not true.First, as many people also know, paramecia sometimes touch each other and exchange nuclear cells.What interests me is: How on earth do they decide when to swap nucleocytes? (That's irrelevant to what I've observed, though.) I did see paramecium bounce off of things, turn around and continue on; but their movements were not mechanical at all—not in the way the textbooks describe them.They travel different distances, bounce back different distances, and turn at different angles in different situations; they don't all turn right or left—everything looks irregular.In fact, we have no idea what they encountered, much less what chemicals they smelled.

One thing I want to observe is, what happens to the paramecium when the water around it dries up?It is said that the paramecium dries out and hardens, like a seed.So I dropped a drop of water on the glass slide and put it under the microscope.I saw a paramecium and some "grass" - to the paramecium, these small grasses already looked like a huge straw web.After more than 10 minutes, the water droplets gradually evaporated, and the paramecium's situation became more and more difficult.It swam back and forth, faster and faster, until it could no longer move, and finally, it was stuck between the "grass sticks" and could not move.

Then, I saw something I had never seen or heard before: the paramecium changed shape and could change shape like an amoeba!It was next to a straw stick and began to fork, like two pincers of a crab.It was divided into about half the length of its body, and suddenly it probably felt that it was no good to go on like this, so it returned to its original shape. So my impression is that the description of these small animals in textbooks is too brief. The fact that none of their behavior is so mechanical or static, these books should really describe them correctly.And if we don't even know much about the diversity of single-celled animals, we can't hope to understand more complex animal behavior.

I also like to observe small insects.When I was about 13, I read a book about insects - it said dragonflies were harmless and didn't sting.But we have called dragonflies "long-legged needles" since we were young, and neighbors think it is dangerous to be stung by them. So if we were out playing baseball or playing and a dragonfly flew by, everyone would scatter and hide, waving and screaming, "Here comes the long-legged needles! Long pins are here! " One day, we were playing on the beach, and a long-legged needle flew by, and everyone was screaming and running around, but I was there like a mountain. "Don't be afraid!" I said, "The book says that long needles won't sting!"

It flew over my foot and everyone was yelling and it was a mess because the long pin was "standing" on my foot.But my amazing science kid, I stubbornly believed that it wouldn't sting me. Maybe many people thought that I was stung in the end——no!This time the book was right.But I really broke out in a cold sweat. At that time, I still had a small toy microscope.I took off the magnifying glass inside and used it to observe things around me.When I was a graduate student at Princeton, I often carried this magnifying glass in my pocket.Once I accidentally took it out to watch the ants crawling around next to the ivy. After seeing it, I couldn't help screaming with excitement.There was an ant and an aphid there.Aphids are a pest, but ants take care of them.If the plant on which the aphid is infested begins to wither, the ants move the aphid to other plants.The ants also benefit from this process by obtaining aphid juice called "honeydew water" from the aphids.

I know all this because my father told me, but I've never seen it with my own eyes. What I saw was an ant walking up to the aphid and patting it with its foot - patting, patting, patting all over the aphid, it was so much fun!Next, honeydew is secreted from the back of the aphid.Under a magnifying glass, honeydew looks like a big, beautiful, shiny, colorful balloon.The reason why it becomes spherical is because of the relationship between surface tension.As for the various lights it gave off, it was because my toy microscope wasn't very good, and the magnifying glass had chromatic aberration - but anyway, it looked beautiful!

The little ant uses its two front feet to move the honey ball off the aphid's back and lift it up!In their tiny world, even water can be lifted one by one!I guess there might be some greasy substance on the ant's feet so that when it lifts the ball up, it doesn't break it.Then, it bites the surface of the honey ball with its mouth, the surface tension collapses, and the whole drop of juice flows into its stomach.The whole process was so much fun! In the dormitory where I live, there is a window protruding to the outside, and the window sill is U-shaped. One day, some ants crawled to the window sill and wandered around.I suddenly became curious and wanted to know: how did they find things?How on earth do they know where to go?Can they tell each other where the food is, like bees?Do they have any perception of the appearance of things?

Of course, these are layman's questions; everyone knows the answers, but I don't, so I'll do some experiments.First, I pulled a rope and tied it to the U shape of the window, folded a piece of cardboard, dipped it in sugar, and hung it in the center of the rope.The purpose of this is to separate the sugar from the ants, so that the ants cannot find the sugar by chance. I want to control this experiment well. Next I folded a lot of small pieces of paper, which are used to transport ants.The papers were placed in two places, some hung on a string, by the side of the sugar; others were placed in an ant-infested spot, and I sat there all afternoon, reading and watching until an ant came to my paper, I moved it to Sugar.

After moving a few ants there, one of them accidentally ran to the next piece of paper, and I moved it back. What I want to see is how long it takes for other ants to know this passage to find food.The result was that it was very slow at the beginning, but then it became faster and faster. I was so overwhelmed with the ants that I was almost crazy. While this was in full swing, I suddenly started sending ants away from the sugar.The question now is, will they crawl back to where they started, or will they run back to where it was just before? After a while, the place where I put the pieces of paper waiting for the ants was very free, and there was not a single ant (if they climbed on these pieces of paper, they could go back to the sugar after I transported them); but in the second place , but there are many ants wandering around looking for their sugar.So I conclude: they all run back to where they were just before. Another time, on the sugar passage leading to the window sill, I put a lot of microscope glass slides and let the ants walk on them.Then, I change the order of the glass pieces, or replace some of the old ones with new ones.I proved that ants are not aware of the appearance of objects, because they can't figure out where things are.If they follow a path to sugar, but there is a shorter path back, they will never find the shorter path. And rearranging the glass pieces also clearly showed that the ants would leave some traces.Next, I easily arranged a lot of simple experiments to see how long it takes for these marks to dry up, whether they are easy to be erased, etc.I also found that traces are non-directional.If I pick up an ant, turn it around a few times, and then put it back, it often doesn't know that it's going in a different direction than before. It doesn't know it's going in the wrong direction until it meets another ant.Later, when I was in Brazil, I met some woodcutter ants (leaf-cutting ant, ants that can bite off leaves), so I did the same experiment, and found that they could distinguish whether they were walking towards food or walking away in a short distance. food.I guess the traces they leave behind are mysterious, maybe a series of smell series: smell A, smell B, space, smell A...and so on. Another time, I wanted the ants to walk in circles, but I wasn't patient enough to complete the experiment; I figured it shouldn't be too difficult to do. One of the difficulties with these experiments is that my breath scares the ants.This must be an instinctive reaction left over from ancient times to escape certain predators who liked to eat them or harass them.I'm not sure if it's the warmth of the breath, the humidity, or the smell that's disturbing them; anyway, when transporting the ants, I have to stop breathing briefly and turn my head so as not to confuse or freak them out. One of the things I really want to figure out is why the ant trails are so straight and nice looking.They seem to be very clear about their purpose, as if they have a lot of geometric concepts; but from the results of my experiments, they don't have any geometric concepts. Years later, I was teaching at Caltech and living in a small house on Alameda Street.One day there were some ants crawling around the tub.I said to myself: "This opportunity is too rare." I put some sugar on the other side of the tub, sat by and watched all afternoon, and finally waited until an ant found the sugar. This part is not difficult, just be patient. Once the ant finds where the sugar is, I pick up the color pen that I have prepared for a long time and follow it to draw, so that I can know the shape of its traces.I already knew, from previous experiments, that ants are not affected by pencil marks, and walk across them without stopping; so my doing so would not affect the reliability of the experiment.However, since the ant seemed to be a little lost on the way home, the line drawn is a bit zigzag, not like a normal ant trail. When the next ant finds the sugar and starts walking back, I use another color to trace the path it took.It is worth mentioning that the second ant followed the circuit of the first ant instead of going back the way it came from.My thought is that when an ant finds food, it leaves a much stronger trail than it normally does when it's wandering around. The second ant walked quickly, roughly following the original track.However, because the traces are crooked and it goes too fast, it often "slips" out of the traces.But when it wanders around, it often finds the right trace again. In short, the route the second ant took home was much straighter than the route the first ant took.As the hurried and careless ants walked through this passage, the traces were "improved" and became straighter and straighter. After tracing eight to ten ants with a pencil, the trace has become a straight line.It's a bit like drawing: first you draw a random line; then draw along it a few times, and after a while a straight line is drawn. As a child, I remember my father telling me what wonderful, social creatures ants are.I also often carefully observe how three or four ants work together to move a small piece of chocolate back to the nest.Interestingly, at first glance, they are indeed surprisingly efficient little guys who work well together.But if you look closely, you'll see that's not the case at all.Judging from their actions, the chocolate seems to be lifted by some magical force. They are pulled randomly from different directions, and during the transportation, one of the ants may even climb on the chocolate.The chocolate was constantly wobbling, moving from side to side, with no common direction—the chocolate didn't arrive at the ant nest smoothly and quickly. Brazilian woodcutter ants are "good" in some ways, but they also have some very interesting stupid habits.In fact, I'm surprised that these habits have survived evolution.It takes a lot of effort for the woodcutter ant to cut an arc on the leaf and take off a small piece of leaf, but after it has finished cutting, there is a 50% chance that it will pull the wrong place, causing the leaf to fall to the ground. And have to start over with another leaf. Interestingly, they never pick up the ones that have been bitten off.So it's clear that woodcutter ants aren't very shrewd in this respect. While at Princeton, ants also found my pantry and found my jam, bread, and other items.The pantry is some distance away from the windows, so there is often such a long line of ants that run across the floor of the room and attack my food.This happened during my various ant experiments, so I thought: Is there any way to stop them from invading my pantry?Of course, I am not referring to methods like poison, because we have to be humane to ants too! In the end, the method I used was this: First, I put some sugar about 8 inches from where they entered the room, but they didn't know it was there.Then, use my transporting technique again - whenever an ant with food comes to my transporter, I take it to the sugar.The ants that are heading towards the food cabinet, if they climb onto the conveyor, I also pick it up and send it to the place where there is sugar. Gradually, the ants found a way to walk back to the ant nest from the place where the sugar was placed, and the traces on the road became stronger and stronger; while the original access to the food cabinet was used by fewer and fewer ants.I know full well that in half an hour or so the marks of the old road will all be dry; in another hour they won't touch my food anymore. The funny thing is, I don't even have to mop the floors.In fact, I was just transporting ants around!