A. Porter 379 
forms as the result of the Herpetomonads being deprived of food, and 
tried the following experiments which confirm this view. 
A Nepa, fed on larvae of Chironomus, was dissected after a few 
hours and the fluid removed from its crop by slight pressure. No 
Herpetomonads were found in this liquid, though naturally I made a very 
careful search. Some of the crop fluid was added to a preparation of 
Herpetomonas jaculum from starved Nepa, and the effect of it on the 
parasites was noted. The Herpetomonads became visibly more granular. 
I consider, therefore, that the presence of granular protoplasm is not 
a criterion of the female sex but is merely a manifestation of great 
metabolic activity. Although some biologists would perhaps hold that 
these granular forms were potential females, I never saw copulation, 
even when these very granular thick forms and thin, non-granular forms 
were intermingled in the same medium. 
Occasionally I have caught sticklebacks ( Oasterosteus aculeatus) with 
Nepa attached to them, their proboscides buried deep in the fish. As 
these Nepa were infected with H. jaculum, the parasite occurred 
naturally mixed with vertebrate blood in the gut contents of Nepa. 
The Herpetomonads also were richly granular forms. Fresh human 
blood from a pricked finger was added to H. jaculum from starved Nepa. 
The protoplasm of the parasites became more granular, their movements 
were more active and longitudinal division occurred. The parasites lived 
for several hours. The granules were those of reserve food material as 
judged by their deep-staining reactions ( intra-vitam ) with methylene 
blue. The Herpetomonas certainly showed no signs of degeneration, 
and this experiment, I believe, conclusively shows that the occurrence 
of many granules in a parasite is to be associated with metabolism, not 
with sex. 
( d ) By measuring many parasites, a series of forms may be obtained 
—from small to large—whose breadth and length gradually increase. 
Where, in a series, is the limit say for male forms to be applied ? It 
seems to me that any such limit must of necessity be artificial, and 
therefore unsatisfactory. Until definite copulation of living flagellates 
has been seen, it is unwise to attempt to differentiate between various 
forms of parasites and to ascribe sex or lack of sex to any particular 
phase of the organism. 
Berliner (1909) and others have asserted, but not proved, that 
autogamy results in cyst production. As autogamy is not a necessary 
accompaniment of encystment, I see no reason why its aid should be 
invoked here, and consider that unless it can be proven, it is well not to 
