228 INFUSORIA. 



the epithelial cells (in the comb, the epidermal cells, as far as the Mal- 

 pighian layer) were penetrated and altered by Coccidia, and that the 

 subjacent tissue was swollen and inflamed, so that the animals were 

 for the most part starved or suffocated. The nature of the disease 

 was placed beyond all doubt, not only by observation, but also by 

 experiment, of which, however, the constant result was that, as before 

 mentioned, only the Coccidia with segmented contents caused infec- 

 tion, while the younger stages traversed the intestine passive and 

 harmless. 



In conclusion, I must once more repeat that the true Coccidia do 

 not include all the forms which investigators of the higher animals 

 have considered Psorospwmice and designated as such. Among the 

 latter I would, for instance, class the "green" Psorospermice,* which 

 Paulicki describes in apes, and which were found in the lungs both 

 of adult and of newly born animals. Their chlorophyll contents 

 are sufficient to exclude them from the Coccidia. 



CLASS III. INFUSORIA. 



Ehrenberg, "Die Infusionsthierchen als vollkommene Organismen : " Leipzig, 1838. 



Dujardin, "Histoire naturelle des Infusoires : " Paris, 1841. 



Claparede et Lachmann, "Etudes sur lea Infusoires," Parts i. et ii. : Geneve, 1858-61. 



Stein, "Der Organismus der Infusorion," Th. i.-iii. : Leipzig, 1867-1878. 



Biitschli, " Ueber die Conjugation der Infusorien," in " Studien iiber die ersten 



Entwickelungsvorgange der Eizelle, die Zelltheilung, und die Conjugation der 



Infusorien : " Frankfurt, 1876. 



Protozoa with a more or less definite body-form, and provided with 

 cilia, which are placed on the body in varying member and arrangement. 

 The protoplasm, especially of the higher forms, is differentiated into an 

 outer layer and a central mass, which sometimes encloses a single nucleus, 

 sometimes more, and very generally one or more contractile vacuoles. 

 With the exception of some parasitic species, all of them have a mouth, or 

 one or more mouth-like openings, serving for the ingestion of food, and 

 most of them have also an anus. 



The name " Infusoria," which has been a familiar word for more 

 than a hundred years, is used to denote those organisms discovered 

 by Leeuwenhoek, which are constantly found in organic infusions, 

 in which indeed they were thought to be spontaneously generated. 

 This is not, however, their proper or normal habitat, which is rather 

 to be sought in stagnant or sluggish water, while its countless micro- 

 scopic contents furnish a rich supply of nourishment to these minute 



1 " Beitrage zur pathol. Anat.," p. 61, 1872. 



