1012 PEOCEEDIXGS OF THE THIKD ENT#9iBfWlCAL MEETING 



words of Leidy. I cite them with due homage to the memory of that 

 American Scientist : — 



" The brownish matter proved to be semifluid, but my astonishment 

 was great to find it swarming with myriads of parasites 

 which indeed actually predominated over the real food in 

 quantity. Eepeated examinations showed that all indivi- 

 duals harbour the same world of parasites, wonderful in. 

 number, variety and form."' 

 Figures 1-6 on Plate 168 show the different forms of Tr. agilis. 

 This protozoon is composed of a kind of head, hyaline and in shape like 

 the head of a mushroom, a kind of neck consisting of two parts, one 

 internal, of the form of an Iwvrglass but with the constriction at the 

 level of the union of its anterior and middle third, and one external 

 ectosarc, enveloping and protecting the ]wurglass-Yi\iQ formation. The 

 neck is inserted above in the middle of the head protruding into its 

 interior and seems like the neck of an open bottle, and below it is attached 

 to the body by its convexity, this articulation being very thin and 

 extremely mobile. The third portion is the body, oval, globulous, 

 susceptible of a very great polymorphism and containing a large nucleus, 

 sometimes hyaline, sometimes full of more or less abundant chromatic 

 granules, and surrounded by a very distinct nuclear membrane. The 

 constitution of the body is thinly granulous and the endoplasm is full 

 of wooden particles, irregularly placed. 



Tr. agilis is covered with flagella, which are disposed in three series : 

 the first one composed of short and immobile flagella, inserted in the 

 ectosarc layer around the neck, the second emerging around the inferior 

 articulation of the neck, and formed by long flagella, covering the 

 anterior part of the body like a surplice ; the third with the flagella 

 shorter than the former, inserted on the whole body and endowed with 

 a limited mobility. 



The flagella of the second series are extremely mobile and this 

 mobility, added to that of the inferior articulation of the neck and to 

 the sarcodic contractions of the body, gives the parasite the most 

 extraordinary forms and is the cause of its extreme polymorphism. 

 The flagella of the third series have been considered by some authors 

 as the longest, of a fantastic length. It is an optical mistake against 

 which I must protest. At first sight these flagella seem really very 

 long, because they are numerous and following one another. Sometimes 

 they cross one another and the best places to determine their length 

 are the lateral borders of the parasite. 



Should they be so extraordinarily long, they would seem still longer 

 when the Trichonynifha shortens : this is never the case and the 



