191G.] NATURAL SCIENCES OF PHILADELPHIA. 19 



nounced that of a female. It possesses, however, the rather densely 

 staining cytoplasm characteristic for the females and the nucleus is 

 too small for a male. The deeply staining granules present in iron 

 hematoxylin material are here in evidence. 



Fig. 22 probably also represents a female since it is a smoothly 

 oval cell with dense cytoplasm, and the nucleus, while large, does 

 not cause any protrusion of the sides of the cell. The radiate nuclear 

 structure in this parasite is peculiar for such an early stage, and may 

 represent a very precocious case of maturation (see p. 30). 



Mouse 126. — This mouse was given the flesh of an infected animal 

 at a stated time and required one-half an hour to complete its meal. 

 It was killed three hours later and in consequence 1 represents the 

 conditions 3 to 3h hours after inoculation. Figs. 23 and 24, Plate II, 

 .ii-e from this mouse and show early male stages, as evidenced by the 

 enlarged nuclei and the scanty quantity of cytoplasm present. 



Mouse 261. — Mouse 261 was given a piece of infected muscle at 

 10 A.M. (Feb. 15, 1915). It began to eat at once and consumed a 

 considerable quantity of the infected material, but did not then 

 complete the meal. At 2 P.M. the mouse was chloroformed, the 

 infected muscle having been eaten in the interim. Hence, it repre- 

 sents the conditions from 4 hours down to some shorter period. The 

 only portions of the intestine examined in this case were int. --1 to 

 int. — 5, or the last five pieces. The intestine of this mouse was slit 

 open prior to fixation and in consequence the spores in the lumen 

 were lost. 



Since the study here was confined to the last few centimeters of 

 the intestine, a given intracellular spore might have been in its place 

 anywhere from a few minutes to three hours or more, and hence it 

 is impossible to pick out the early female stages with any degree of 

 certainty. Thus, fig. 25 might be either that of an early female 

 stage or of a parasite which had been in the cell for only a short time. 

 It is perhaps the same with fig. 26 which represents a form difficult 

 to classify satisfactorily. On the other hand, fig. 27 is an evident 

 early male, and both this and fig. 26 are of interest in showing very 

 clearly the nuclear structure. 



In a few cases, in mouse 261, males were found in which the lo- 

 ot cytoplasm was complete 1 . 



MouS( '.',7. — This mouse was killed four hours after feeding. It- 

 intestine was cut into 34 pieces, from int. 1 to 34, and observations 

 were made on int. 12, 14, 16, 19, 30, and 33. 



The differentiation into males and females is here carried ;i little 



