330 THE MICROSCOPIST. 



faction of organic bodies, fungi are important agents. 

 In the former vibrios are found, and in the latter monads 

 and bacteria. Decay is arrested if access of fungus germs 

 is prevented. Putrefaction is as dependent on bacteria as 

 the fermentation of non-nitrogenous bodies upon yeast- 

 fungi. 



Many acute infectious diseases are considered to pro- 

 ceed from fungi, although the reasons for such an opinion 

 are chiefly theoretical, arising from the presence of fungi 

 in those diseases. Such are diphtheria, pyaemia, puer- 

 peral fever, small-pox, etc. Many experiments have been 

 made, by inoculation, etc., but thus far with little results. 

 Observers differ greatly concerning the same disease, the 

 specific fungus of one being disavowed by another. Still, 

 much light may be expected respecting aetiology from ob- 

 servations of this kind. 



II. ANIMAL PARASITES. 



These inhabit either the external surface (epizoa) or 

 internal organs (entozoa). 



I. PROTOZOA. 



GREGARINIDJE. See page 180. Gregarinidce are para- 

 sitic animals, generally regarded as the lowest of the pro- 

 tozoa, although this opinion is doubtful. They usually 

 consist of a single cell, with an illy-defined membrane 

 filled with granular and fatty sarcode, with nucleus and 

 nucleolus. They are developed much like protophytes, 

 page 140. The gregarina becomes motionless, globular, 

 and encysted. The nucleus then disappears and the sar- 

 code breaks up into little masses which become pointed 

 at each end (pseudo-navicellse). These masses escape as 

 amoeba, page 121, and develop new gregarince. 



Globular psorospermice, as they are called, have been 



