26 RESEARCHES IN HELMINTHOLOGY AND PARASITOLOGY. 



Diniensiofis. — I^eiigth of filaments i -500th to i-75th inch; greatest 

 breadth i -1700th inch. 



Habitat. — Grows in ])rofusion from the mucous membrane of the 

 ventricuhis of Passa/us cornutus. 



Besides the foregoing I hav^e found numerous free or floating 

 entophyta in the contents, usually of the posterior part of the ali- 

 mentary canal, in mammalia, aves, reptilia, pisces, mollusca, insecta, 

 &c. These, at present, I do not feel at liberty to describe as new 

 or peculiar, from my want of acquaintance with cryptogamic botany. 

 A number of them, I have no doubt, if not peculiar, at least con- 

 tinue to grow luxuriantly in the intestinal canal ; such are various 

 Mycodenna, &c. ; others very probably are swallowed with the food, 

 and pass from the intestinal canal unchanged. Numerous drawings 

 of these I exhibit to the Academy, and purpose leaving them to 

 future investigation, or to the consideration of cryptogamic botan- 

 ists, being a field well worthy of their researches. I also have a 

 number of others, the character of which is peculiarly entophytic ; 

 but these I have not yet studied out nor figured, but hope to pre- 

 sent descriptions of them to the Academy in a very short time. 



[February. 1850. No. 50. See Bibliography,] 



Dr. Leidy stated it was now eighteen months since he had sought 

 for Entophyta within living animals, having been previously im- 

 pressed with the belief of their existence upon reflecting upon the 

 essential conditions of life. Four months since he exhibited to the 

 Academy numerous drawings and specimens of Entophyta obtained 

 from living animals ; he now exhibited others. 



The essential conditions of life are five in number, viz., a germ, 

 nutritive matter, air, water, and heat. The four latter undoubtedly 

 exist in the interior of living animals, animal or entozoa germs also 

 are well known to exist, and it was rendered extremely probable 

 that vegetable germs would also exist, and with them all the con- 

 ditions necessary to vegetable growth. Plants have been very fre- 

 quently observed growing upon the exterior of animals, and less 

 frequently upon the interior, most usually upon diseased surfaces, 

 but the growth of such parasites had not been pointed out as a 

 normal and common condition as in the case of entozoa. 



Dr. E. next reviewed the theory of generation. He inclines to 

 the opinion that sexual elements are absolutely necessary for the 

 perpetuation of germs. He considered the alteration of generation 

 in certain animals no objection to the law, for after successive de- 

 velopments an admixture of sexual elements is ob.served to be neces- 



