Sarah Ann Hackett Stevenson

“ People have been trying to prove for two hundred years or more that these little specks of life can make themselves. Some time I will tell you how you can prove that this is not true. These little torulæ float about in the air, or sleep in any dry place, never showing that they are alive till they are planted in some nest or nidus. When the cook dries her yeast-cakes, she puts all the little torulæ to sleep, and there they go into winter quarters, or hibernate in their cells, like the bears in their caves. ”

“ The sunlight is the fire by which this chemist heats his crucible, or melting-pot. Into this crucible he puts the poisonous gas, carbonic acid, that he gets from the air, and melts it up into carbon and oxygen, the two substances of which it is made. He keeps the carbon to feed upon, and gives back the pure oxygen to the air again. Thus he works from sunrise to sunset. His hours are regulated by the sun, instead of by Congress. You never hear of an "eight-hour movement" or a "strike" among the chlorophyll laborers. As soon as the sun goes down they go to bed, like honest workmen. ”

“ So much for the outside sac of the cell—now for the inside. The cell-jelly, or proto-plasm, is made of water, fat, mineral matters, and protein. The water we already know. The fat is made of carbon, hydrogen, and oxygen. The minerals belong to the simple elements.
The protein we know but little about. We are sure that it contains carbon, hydrogen, oxygen, and nitrogen, with a little sulphur or phosphorus, or both, and we know that it is found in all living matter. There is no life without it, so it has been called the "basis of life." ”

“ First, one stumpy foot is put out as far as it can reach, then the body all runs into the foot, and another foot is stuck out from some other part, and away goes the body into this new foot. So it gets on, the feet actually swallowing
the body! The toad sometimes swallows its old skin, but the amœba is the only animal I know which is "taken in" by its feet! How odd it would be, if, as you walk along, you should suddenly disappear into your boots! If you crush the amœba, you find no trace of a tough sac such as you found in the yeast and protococcus cells. ”

“ During the night, while these green-leaf or chlorophyll workers are asleep, the colorless protein-jelly of the cell gives out the poisonous carbonic acid and takes in oxygen. The green cells give off carbonic acid and take in oxygen during the day, as well as during the night, but the little chlorophyll-grains do so much more work than the rest of the jelly in the cell, it seems as though the cell gives out nothing but oxygen and takes in nothing but carbon during the day, when all these little colored chemists are doing their best. ”

“ The word protein means first or chief, and this is the part of the protoplasm-jelly, which is alive. The kernel, or nucleus of the cell, seems to be only a part of the protein-jelly which is harder than the rest, and it has something to do with the making of new cells, as we shall see farther along in our study.
Now, what about the dye-stuff? Is it of any use, or is it just here to make the mould look pretty? It is of great use, as we shall soon see. Each grain is a very clever little chemist that works in the cell, which is his laboratory, or workshop. ”

“ As the screw propels the water through the branchial or gill chamber the blood takes out the oxygen from the air in the water, and gives back carbonic acid. You remember how the strong hairs (cilia) of the pockets sweep the water along over the mussel's gills, and how the little blood-vessels take up their oxygen and give up their carbonic acid. The gills that are fastened to the legs move when the legs move, and the faster they go the more water they use. So much for the lobster's breathing or respiration. ”

“ Now, if you examine some of the protococcus that grows in old water, you will see the cells sculling about very fast, like so many little boats. If your eyes and microscope are very good, you can see the two tiny oars by which the little boatman guides his craft. There seem to be two kinds of boats—one small, green, and pear-shaped (Fig. 10) ; the others are larger, and look more like the carpenters' houses. The little pear-shaped boats often have a tiny red window, or port-hole, called the "eye-spot." ”

“ When the sun is shining they purify the air, because they give off more oxygen than carbonic acid; but at night they poison the air, because they give off only carbonic acid.
All plants that contain this green-leaf matter, or chlorophyll, are called green plants. You remember the colorless plants, such as toad-stools, are called fungi. It is found, as you have seen, that green plants must have the sunshine, but fungi grow as well, or even better, in the dark. Thus we have found the materials out of which the mould-cell is made, and the use of all its different parts. ”

“ If you press some of the
cells lightly they will burst, the soft inside part will flow out and leave the empty sac just the shape of the cell except where it is torn. This shows that the outside is much stronger and tougher than the inside. Chemists have found that this wall of the cell is made exactly the same as the tough cells of wood—it is called cellulose.
The light-colored jelly inside the sac has a long name of its own—protoplasm—which means first form or mould, because this seems to be the first form of all life. The green and the red colored grains are called chlorophyll. ”

“ Now, I dare say you are wishing to hear about the lobster's bairns or little ones. The lobster's eggs are covered by a soft, sticky glue, which fastens them to the long hairs which cover the paddles under the abdomen (Fig. 22) . The good mother-lobster doubles up her body so that the eggs are all folded inward safe from harm. Hundreds of eggs are carried in this way, and when the lobster is boiled they turn red and form what is called the coral. The baby-lobsters differ greatly from their parents. Their eyes are very large, and set in the head instead of on eye-stalks. ”

“ It is enough to open any one's eyes to think of the thousands of these odd creatures that go half creeping, half walking through one's veins. You know people sometimes talk about their "blood crawling," but very few people know how the blood crawls. ”

“ Of course, as he grows, his shell gets too small, but, instead of putting on an addition as the mussel does, he leaves the old house altogether and builds a new one. In three days after the lobster moves out of the old house he has been found all settled in a bran-new one one-third larger. Two round balls are often found in the lobster's stomach, and people call them "crab's-eyes." These balls are made of lime, which it is said the lobster has been storing up for his new shell. Thus the lobster moves "out of the old house into the new" every year till he gets his growth. ”

“ Pear-shaped Cell without a Sac, or the Boatman without a Boat.
means eyelashes. When the little sailors are getting tired, and just before they die, you can see these eyelash oars quite plainly, they move so slowly; but, when they are vigorous and the day is sunny, the oars move so fast you cannot see them. No Columbia or Cambridge crew can begin to pull with these protococcus boatmen. Besides being good oarsmen, they are also good builders. You may often see them breaking up the old boats by cleavage and fission, just as the carpenters break up the old houses. ”

“ At first you might think them whiskers, as they grow out around the mouth, but tentacle means a feeler or holder, and with its tentacles you will see how our little friend feels and holds its food, and carries it to his mouth, almost as you use you fingers. ”

“ He has another odd way of laying down his arms when he is frightened by a great noise, such as thunder, or the tiring of a cannon. It is no uncommon thing to find a number of these broken swords lying about among the rocks, showing where there has been a lobster fright or fight. ”

“ If you stain with magenta or iodine, the whole cell becomes colored alike. If there were a tough, woody sac, as in the yeast and mould, it would not be stained. The iodine does not give it a blue color, so there cannot be any starch in the amœbæ. The amœbæ grow like the green-mould cells, by fission, that is, by one or two partitions made through the old cells. You will first see two kernels appear in one of the old cells; then, by close watching, you see a partition going right down between the kernels, separating the old cell into two, with a kernel or ”

“ There is also a green protococcus that grows in the snow regions, and it is called the "green snow-plant." The red and the green snow-plants do not grow just in the same way as the protococcus of the trough or paling. ”

“ The nerve which goes to the eye is called the optic nerve, and it is connected with each square by pretty rods and cones, which look like those in your own eye (Fig. 27) . The rods and cones are covered with coloring-matter or pigment, which turns red when it is boiled. ”

“ None but the finest particles can pass through the strainer, and hence this pylorus is a very good gate-keeper. The intestine does not go wandering about in the body like the mussel's, but passes straight back (Fig. 22) , and ends at the anus, at the under part of the tail-piece (telson) . On each side of the cephalo-thorax lies a long, soft, yellowish-green mass. This is the liver, and it opens into the small, pyloric end of the stomach by several ducts or pipes on each side. Away up in the front part of the cephalo-thorax, at the base of the feelers (antennæ) on either side ”

“ Hydra fishing for Food with its Feelers or Tentacles.
light, but not in the sun, and in a few hours you will find a good many of these little creatures clinging to the side of the glass toward the window. They hold on to the glass by one end, and all around the other end, which is wider, are a number of long threads called tentacles, hanging down gracefully in the water. ”

“ From all this you see that the mouth of the lobster is well armed with teeth and scissors to tear and cut its food. Counting from the front, it has first the true jaws (mandibles) ; then the two pair of little jaws (maxillæ) ; and these are followed by the three pair of foot-jaws (maxillipedes)
making, altogether, six pair, which are all turned up against the mouth. In front of the jaw are two very long jointed feelers called antennas, but you seldom see them at their full length (Fig. 15) ; they are easily broken (Fig. 19) . Next to the feelers (antennæ) are two ”

“ The paddles on the last or sixth somite are different from the others; they are wider and turned backward (Fig. 15) so as to lie at each side of the tail-piece, telson; and these great-fingered paddles, taken with the telson, form what is called the tail-fin. ”