PSEUDOSPORA VOLVOCIS, CIENKOWSKI. 928 
tween two or more individuals. In the cases I observed the 
creatures separated after about fifteen to thirty minutes. The 
process is very rarely to be seen, and occurs more frequently 
within the Volvox than in the free state. This might possibly 
be a step towards the formation of plasmodia. Protomonas 
and Protomyxa, nearly allied genera, form plasmodia, but they 
are not known to occur in either Vampyrella or Pseudospora 
aculeata. I have, however, not sufficient evidence to draw 
any conclusions as to the meaning of this phenomenon. 
Pseudospora, when attacking the Volvox, attaches itself 
firmly to the colony by pseudopodia; these are extended 
apparently indifferently from the non-flagellate end of the 
creature or else from either side. 
When newly arrived in the Volvox or while still on the out- 
side the animal is very sensitive to any change of conditions ; 
for instance, rise of temperature, evaporation of the water, or 
stoppage of the motion of the Volvox will cause the creature to 
leave the colony; this is to be seen even in starved individuals. 
The processes above described—alternation of the flagellate 
and amceboid condition and reproduction by fission—continue 
for some time (fourteen to twenty-one days) and then a different 
form of reproduction appears. 
GAMETOGENESIS AND CONJUGATION. 
In the amceboid Pseudospora there are developed spheres 
of a clear greyish appearance. ‘he number of these to be 
found in a single individual varies; in one culture one- and 
two-sphered forms greatly predominated, in another I found 
individuals with three or four and on one occasion with eight 
spheres. The individual in which the spheres arise does not 
form any kind of cyst. The pseudopodia are not withdrawn ; 
in some cases the flagella persist, and movement and feeding 
may still go on after the spheres are a considerable size. 
Finally, the protoplasmic body surrounding the sphere dis- 
integrates, but the time at which this occurs varies greatly in 
relation to the state of development of the sphere. The pro- 
