7O E. A. ANDREWS. 



The times consumed in the various elements of this alternation 

 of phases vary very greatly, being hastened by high tempera- 

 tures in general. Often the animals that have been feeding 

 adults during the night pass into the swimming form in the 

 morning, settle down toward the middle of the day and transform 

 into adults again before night so that an entire wave of rise to 

 the adult and recession to the swimming form and rising again 

 to the adult may be about 24 hours. However, in some cases 

 an entire alternation was accomplished in perhaps as little as 

 6 hours. 



The following anecdote relating to a single individual folliculina 

 acting under unusual conditions may serve to illustrate the 

 pertinacity with which these alternating phases are adhered to 

 and to raise a number of questions which it would require experi- 

 mentation to solve. 



August 28, 1914 which was very near the end of the season for 

 the occurrence of Folliculina in the Severn River, a number of 

 perfect animals in their houses were placed in a hanging drop 

 over water in a hollow slide for the purpose of seeing how they 

 retrograde into the free-swimming form. One group had 17 or 

 1 8 perfect cases, another had 5. 



By some accident one of these cases had the tube jammed at 

 the tip so that it was closed off. August 29 at 7:50 A.M., 

 temperature 75 F., the folliculina in this tube which from its 

 color was evidently an old one, not recently formed, was found 

 to be in a late stage of reduction of the arms in the process of 

 becoming a free-swimmer (Fig. i). It revolved on its foot as 

 normal, with reversals of direction and the arms had been, as 

 it were, melted down to a castellated ridge or membrane while 

 the long complex adoral zone was now but a semicircular band 

 running along the edge of the very obliquely truncated end of 

 the body, opposite to the above elevated ridge. At 9:50 the 

 arms were reduced to nothing and the folliculina was ready to 

 break loose as a free-swimmer with normal spiral adoral band 

 (Fig. 2). This larval stage then broke free from its foot and 

 proceeded to go out of the tube as is normal, but was prevented 

 from emerging by the closure of the tube near its tip. Then 

 began a long series of advances and retreats in which the free- 



