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THE AMERICAN NATURALIST [Vol. XL VI 



before total lapse, still bore developing embryos in their 

 diminutive bodies. 



The typical case of relationship, however, is, plainly, 

 for a few generations of rapidly developing saccates to 

 be succeeded, after a few transitional forms, by a con- 

 tinuous and ever-increasing population of the humped 

 type. 



As to the occurrence of the humped type, this is, prac- 

 tically, as just stated. Although never hatching from the 

 resting egg, it soon supplants the smaller and earlier 

 form and then continues to multiply, in favorable local- 

 ities, until put an end to by drought, rain, or the exhaus- 

 tion of the food supply. I do not believe that it can mul- 

 tiply indefinitely, however, for in even my largest aquar- 

 ium jars, the species invariably seems to die out after 

 several crescendos and decrescendos of development. 

 The largest cultures have lasted about five months. That 

 their death is not due to the accumulation of metabolic 

 products in the unchanged water seems probable, because 

 in one case a new generation hatched from resting eggs 

 soon after the death of the first, and showed no signs of 

 weakness, although growing in the same long-used 

 medium. 



The occurrence of the giant campanulate form is a to- 

 tally different matter from that of the other two types. 

 It never occurs alone. It never occurs in newly hatched 

 cultures or young stocks. 4 It rarely occurs in great 

 numbers, and never does it do so, so far as I have ascer- 

 tained, in nature when feeding upon what may be called a 

 normal food. On the other hand, in old stocks that have 



written, the experiment has been made of hatching out hundreds or thousands 

 of resting eggs in a very small space-e. g., a three-oz. bottle, in almost 

 pure tap water. The results of this experiment are very striking. Placed 



of both the humped and the campanulate types. In juS what generation 

 tmn appear is not known, but very probably in the second and third 



the majority starving to death or serving for food only. 



