ANIMALCULES AND ENTOZOA. 527 



cording to the different species of matter em- 

 ployed. Those simple organizations termed 

 entozoa, generated in the parenchymatous sub- 

 stance of many animals, without the visible ex- 

 istence of any parents, eggs, or germs, also vary 

 according to the nature of the animal, and even 

 of the organ in which they are formed.* Nor 

 is there anything more mysterious in this, than 

 in the ordinary process of generation, only that 

 we are more accustomed to the latter ; or that 

 specific contagions should be generated by 

 certain combinations of filth, and vitiated animal 

 secretions, as in gonorrhea, lues venerea, small 

 pox, the itch, &c., that have the power of propa- 

 gating themselves in a mode analogous to the 

 production of fermentation by yeast; which, 



* It is said that twelve different species of entozoa have been 

 found in man, six in the alimentary canal and its appendages, 

 one in the lungs, one in the brain, one in the eyes, one in the 

 muscles, one in the kidneys, one in the ovaries, and one in the 

 skin : while in the several organs of the sheep, nine species have 

 been discovered ; eleven in the ox ; nine in the horse, hog, and 

 fox ; and eight in the hare. They have been found in birds, rep- 

 tiles, fishes, Crustacea, and mollusca. (See Fletcher's Rudiments 

 of Physiology, part ii. p. 12.) 



They have also been found in the embryons of these animals ; 

 from which it is maintained by Pallas, Miiller, Werner, Bloch, 

 Goeze, Braun, G. R. Treviranus, Rudolphi, and others, that 

 they are the products of non-assimilated matters, or morbid 

 productions formed in the humours or parenchyma of the or- 

 gans, in a mode resembling the generation of infusoria during 

 the fermentation of organic matter. (Tiedmann's Comp. Phy- 

 siology, p. 40.) 



