Philodinaea.} THE INFUSORIA. 399 



flow away. For observing this action with effect, finely 

 divided carmine or indigo must be mixed in the water. 

 The nutritive apparatus commences with a ciliated mouth, 

 opening anteriorly, just beneath the hook-like proboscis : 

 the cavity of the mouth is a long extensible tube, having 

 posteriorly an oesophagal head, with four muscles, and two 

 striated jaws with double teeth (zygogomphia) . The reso- 

 phagus communicates with a filiform alimentary canal, 

 which runs along the body, and has posteriorly an oval 

 expansion near its opening, at the basis of the tail-like 

 foot. A thick glandular cellulose mass, often yellowish or 

 greenish, surrounds the alimentary canal; its use is un- 

 known : Dr. Ehrenberg thinks it may be a coecal append- 

 age, or sexual glands : anteriorly are two biliary glands. 

 The propagative system is very interesting : the ovarium 

 is a globose glandular mass ; in it four or five ova some- 

 times so completely develope themselves, that the young 

 creep out of their envelopes, extend themselves, and put 

 their wheels in motion while in it. They sometimes occupy 

 two-thirds the length of the parent. In the ovum the 

 young are disposed in a spiral bent manner : a sexual vesicle 

 exists. The vascular system comprise eleven or twelve 

 parallel transverse vessels, and the respiratory tube at 

 the neck. The latter was formerly considered a sexual 

 organ. The two red frontal eyes, with ganglion beneath 

 them, are indications of a nervous system. These eyes 

 are cells, filled with a granular pigment, which sometimes 

 separate abnormally into several ; so that Dr. Ehrenberg 

 thinks no crystalline lens exists, but, it may be, they are 

 compound, like the eyes of insects, to determine which 

 will require a microscope possessing enormous penetrating 



