1914.] NATURAL SCIENCES OF PHILADELPHIA. 435 



than microgametes. As seen in sectioned material, the microga- 

 metes are from 2 to 2.5 microns long, with both ends pointed, but one 

 noticeably broader than the other. They are characterized by an 

 intense affinity for chromatin stains. Stages such as these may 

 occur as early as nine hours, but it is not until later that they become 

 abundant. They reach their full development at the end of 18 

 hours, and, so far as my studies have yet gone, are no longer present 

 at the end of 24 hours. 



It is only in their later developmental phases that the females can 

 be picked out with any certainty. They are illustrated in figs. 

 10 and 11, which show oval elements containing a vesicle in which 

 is a chromatin body. In the 18-hour stage all of the parasites 

 present, with a certain exception to be noted below, are either in the 

 condition shown in figs. 7, 8, and 9, or that shown in figs. .10 

 and 11. As was stated above, however, the parasites taken to be 

 early male stages were apparently only nuclei, since if any cytoplasm 

 were present it was reduced to an extremely fine peripheral film. 

 This conclusion was based not only upon the history of these bodies, 

 but also upon their appearance. On the other hand, the bodies 

 shown in figs, 10 and 11 have all the appearance of complete cells, 

 with a considerable bulk of cytoplasm. It may then be that from 

 the very outset some of the parasites retain a part or the whole of 

 their cytoplasm, these being destined to produce the macrogametes. 

 This surmise receives a certain amount of support from what is seen 

 in fig. 6. This parasite appears to have retained at least the 

 greater part of its cytoplasm. But we have here the representative 

 of a condition found nine hours after feeding, whereas the loss of 

 cytoplasm on the part of those parasites which suffer this depriva- 

 tion may be completed as early as 2J to 3 hours. It may then be 

 suggested that fig. 6 represents an early female stage, and if this 

 be so it would follow that the females retain most if not all of their 

 cytoplasm. It may also be noted that in the periods from 9 to 18 

 hours parasites which are clearly females show phenomena which 

 suggest maturation. 



Finally, in the 18-hour period there is to be found the condition 

 illustrated in fig. 12. This shows a parasite in all respects like 

 figs. 10 and 11 except for the presence in the cytoplasm of a 

 sharply staining chromatin body. It does not seem unreasonable 

 to look upon this as a microgamete which has fertilized the 

 macrogamete. 



29 



