- Proterospongia
One of the simplest multicellular animals, illustrating the beginning of a body. There is a setting apart of egg-cells and sperm-cells, distinct from body-cells; the collared lashed cells on the margin are different in kind from those farther in. Thus, as in indubitable multicellular animals, division of labour has begun - Volvox
The Volvox is found in some canals and the like. It is one of the first animals to suggest the beginning of a body. It is a colony of a thousand or even ten thousand cells, but they are all cells of one kind. In multicellular animals the cells are of different kinds with different functions. Each of the ordinary cells (marked 5) has two lashes or flagella. Daughter colonies inside the Parent colony are being formed at 3, 4, and 2. The development of germ-cells is shown at 1. - Diagram of amœba
The amœba is one of the simplest of all animals, and gives us a hint of the original ancestors. It looks like a tiny irregular speck of greyish jelly, about 1/100th of an inch in diameter. It is commonly found gliding on the mud or weeds in ponds, where it engulfs its microscopic food by means of out-flowing lobes (PS). The food vacuole (FV) contains ingested food. From the contractile vacuole (CV) the waste matter is discharged. N is the nucleus, GR, granules. - Early Life-History of the Salmon
1. The fertilised egg, shed in the gravelly bed of the river. 2. The embryo within the egg, just before hatching. The embryo has been constricted off from the yolk-laden portion of the egg. 3. The newly hatched salmon, or alevin, encumbered with its legacy of yolk (Y.S.). 4 and 5. The larval salmon, still being nourished from the yolk-sac (Y.S.), which is diminishing in size as the fish grows larger. 6. The salmon fry about six weeks old, with the yolk fully absorbed, so that the young fish has now to feed for itself. The fry become parr, which go to the sea as smolts, and return as grilse. In all cases the small figures to the right indicate the natural size. - Nautilus
A section through the Pearly Nautilus, Nautilus pompilius, common from Malay to Fiji. The shell is often about 9 inches long. The animal lives in the last chamber only, but a tube (S) runs through the empty chambers, perforating the partitions (SE). The bulk of the animal is marked VM; the eye is shown at E; a hood is marked H; round the mouth there are numerous lobes (L) bearing protrusible tentacles, some of which are shown. When the animal is swimming near the surface the tentacles radiate out in all directions, and it has been described as "a shell with something like a cauliflower sticking out of it." The Pearly Nautilus is a good example of a conservative type, for it began in the Triassic Era. But the family of Nautiloids to which it belongs illustrates very vividly what is meant by a dwindling race. The Nautiloids began in the Cambrian, reached their golden age in the Silurian, and began to decline markedly in the Carboniferous. There are 2,500 extinct or fossil species of Nautiloids, and only 4 living to-day. - The Skull and Brain-Case of Pithecanthropus
The java ape-man, as restored. By J. H. Mcgregor from the scanty remains The restoration shows the low, retreating forehead and the prominent eyebrow ridges. - Skeletons of the Gibbon, Orang, Chimpanzee, Gorilla, Man
Photographically reduced from diagrams of the natural size (except that of the gibbon, which was twice as large as nature) drawn by Mr. Waterhouse Hawkins from specimens in the Museum of the Royal College of Surgeons. - Surinam Toad (Pipa Americana) with Young Ones Hatching out of Little Pockets on her Back
In the case of the thoroughly aquatic Surinam Toad (Pipa), the male helps to press the eggs, perhaps a hundred in number, on to the back of the female, where each sinks into a pocket of skin with a little lid. By and by fully formed young toads jump out of the pockets. - An Eight-Armed Cuttlefish or Octopus Attacking a Small Crab
These molluscs are particularly fond of crustaceans, which they crunch with their parrot's beak-like jaws. Their salivary juice has a paralysing effect on their prey. To one side, below the eye, may be seen the funnel through which water is very forcibly ejected in the process of locomotion. - Wing of a Bird, Showing the Arrangement of the Feathers
The longest feathers or primaries (PR) are borne by the two fingers (2 and 3), and their palm-bones (CMC); the second longest or secondaries are borne by the ulna bone (U) of the fore-arm; there is a separate tuft (AS) on the thumb (TH).