OBSERVATIONS ON THE PROTOZOA 
339 
This most interesting and problematic species lias been taken 
regularly in large numbers from gold fish tanks about town. 
Given moderate warmth and quiet the individuals rapidly in- 
crease in size and numbers for a few weeks, when they die off 
and a new culture must be started. In a sluggish condition 
the animal resembles Actinophrys sol, or it may at times with- 
draw nearly all of its rays ; but in active state it becomes the 
