Plate 4. 
PROTOZOA. INFUSORIA. SPONGIA. RHIZOPODA. 
A drop of water, when viewed through the microscope, reveals to the eye of the ob- 
server a whole world of animated beings. This fact was discovered some 200 years ago 
by the celebrated Dutch naturalist, Leeuwenhoeck, who in order to investigate the sting- 
ing properties of pepper placed some ground peppercorns in water and after letting the 
mixture stand a while viewed the same through his microscope, when to his astonishment 
he found the water swarming with minute living creatures, wriggling, fighting and devour- 
ing one another. He had in fact discovered one of the lowest stages of animal life, the 
Infusoria, the nature of which are to this day problems which have not yet received any 
thoroughly satisfactory solution. The celebrated Naturalist, Ehrenberg of Berlin, was the 
first to throw light upon this branch of Natural History, and his investigations went to 
show the enormous diffusion and the vastness of the numbers, in which the manifold forms 
of Infusoria are met with in all waters, and to prove that reproduction is effected, as in 
the case of others among the lowest forms of animal life, partly by means of eggs and 
partly by spontaneous division. 
Our illustrations represent some of the most interesting forms, which are met with 
in water all over Europe. 
1, The Stentor Roeselit is shown in its two varieties of shape: compressed, which form it 
takes when swimming, and spread out like a trumpet. It may be observed with the naked eye. 
2. The Vorticella Convalaria is one of the prettiest of the Infusoria. Attaching itself, 
generally in large groups, by its delicate flexibie stem to some fixed object, it stretches 
out its bell-shaped body, the open end of which is surrounded by tentacles, in all direc- 
tions to catch its prey. 
3. The Bursaria Vorticella has the edges of its body fringed with fine hairs, which 
it uses to propel itself with. 
4. The Ophryoglena Acuminata, has a red eye and a brown body covered with fine hairs 
and terminating in a tail 
5. The Stylonychia Lanceolata is furnished with spines on the upper and lower por- 
tion of the body and about the mouth, which enable this very voracious animalcule to 
climb about among plants. 
6. The Trachelius Ovum has a broad egg-shaped body with a large mouth and a 
plainly visible digestive canal. It is found in bog-water. 
7. The Leucophrys Sanguinea is covered with fine moveable hairs all over its body. 
Our illustration shows an individual in the act of reproduction by spontaneous division. 
The Rotatoria were formerly included among the Infusoria. The more critical researches 
of modern investigators have however led to their being classed with the Articulata. They 
are most minute beings, the largest specimens being scarcely 1/3 of a line in length, and owe 
their name to the wonderful organs, with which they propel themselves. These are situated 
around the mouth and consists of two semicircular arms, covered with numerous fine cilia, 
which on being set in motion produce the impression of a wheel in rotation. They are 
found all over the world, both in fresh and salt water. 
8. The Rotifer Vulgaris can compress and distend its body at pleasure. — 
The Sponges, Spongiw, are only found in the sea. For a long time it has been a 
disputed point whether to class them among the animals or the vegetables. Their external 
pEpeenee which allows of the utmost possible variety of shape would justify the latter 
theory, while their internal organisation is decidedly that of an animal. The body which 
grows slowly, firmly attached to the bottom, is perforated in every direction by innumer- 
able pores, which imbibe the water and extract aliment from it. The genus is divided 
into two sections, the Calcispongie and Halispongie, which are distinguished by their 
fibres being strengthened by calcareous and silicious spicula respectively. 
9. The Aainella Polypoides belongs to the Halispongie, and is found in the Adriatic. 
It grows to the length of 18 inches. 
10. The Spongia Manus, so called from its resemblance to the human hand, is also 
found in the Mediterranean. — 
The Rhizopoda constitute the lowest form of animal life. A delicate, and often 
beautifully articulated shell encloses the gelatinous mass of the body, light moveable fila- 
ments extending from the openings of the shell, and serving to propel the animalcule and 
enable it to catch its food. They appear in myriads, the sand and mud at the bottom of 
the sea swarming with them. 
11. The Nonionina Germanica, a very beautiful species, is very common in European 
waters, and noted for its voracity. 
12. Tho Noctiluca Miliaris appears in countless myriads on the surface of the ocean, 
producing the exquisite phosphorescent gleam so often seen at night. 
