poetek: teichonympha. 63 



has seemed to me to be a production resulting from change due to disso- 

 lutiou." It does not appear from anything said elsewhere, or from his 

 drawings, that he connected the presence of this caudal appendage with 

 the vibrating cord. 



The method employed in removing from the host the living animal- 

 cules for study has proved to be important, for it is to this that I owe the 

 discovery of the peduncle previously desci'ibed. Leidy speaks of gently 

 pressing the intestine of the host, and thus forcing out the parasites. 

 Instead of doing this, I removed the intestine into normal salt solution 

 and on the slide teased it into pieces with needles. In this way of course 

 many fragments of the intestine were found mingled with the parasites. 

 These were frequently covered with Pyrsonymphse, so closely packed 

 together that they looked at first sight like large epithelial cells. Each 

 of the parasites was attached to the fragment of the intestinal wall by a 

 long filament (Plate 4, Fig. 45). I think that Leidy saw this filament 

 or peduncle, as I have already called it, for he says ('77, p. 438), "In 

 the process of dissolution of the animal, the undulating cord [flagellum] 

 often appears to project to a variable extent from the narrower end of 

 the body " ; but he did not recognize that this projecting part was a 

 means of attachment, for on forcing Pyrsonymphse from the intestine 

 the most of this peduncle must invariably have been broken off. !N"or- 

 mally, I believe, all mature Pyrsonymphfe are attached to the intestine 

 by means of this peduncle. 



The few evidences of reproduction which I have observed relate to 

 the conditions of the nucleus or the size of the individuals. I have 

 observed nuclei in what I believe to be various stages of division 

 (Plate 4, Figs. 48, 49, 55). This shows that probably reproduction by 

 division takes place occasionally. Perhaps Figure 53 represents an in- 

 dividual recently formed in this way ; the presence of the nucleus in the 

 posterior portion of the parasite certainly points to that conclusion. 

 Individuals produced by the division of a large adult Pyrsonympha 

 should of course resemble the adult form in the almost total absence of 

 cilia, and also in tlie possession of a flagellum. It therefore seems safe 

 to assume that almost all unusually small Pyrsonymphse possessing these 

 qualities (Plate 5, Figs. 62, 64) were recently formed by division. 



Besides young of this type, there are found swarms of immature Pyr- 

 sonymphse with essentially different characteristics. These are, for ex- 

 ample, profusely covered with fine, short cilia of nearly equal length 

 (Plate 5, Figs. 58, 61, 63). Apparently, the flagellum is frequently 

 wanting in these forms, or at least cannot be distinguished (Figs. 57, 



