^ESTIVATION OF BOTRYLLOIDES GASCOI DELLA VALLE. 



157 



day adult zooids with large buds would be seen, all remains of the previous gener- 

 tion having disappeared. In one case Period 1 was omitted entirely, the siphons of 

 the younger generation opening before those of the older one had closed. The fol- 

 lowing table gives some scattered quantitative data recorded at the time when the 

 observations were made. 



Table III. 



A + or — after a figure means the period in question lasted a little longer or shorter than the number 

 indicates. 



A. Incbease in interval between adult zooids. — From the foregoing facts 

 it is seen that as the conditions become more unfavorable the length of Periods 1 and 

 3 between successive generations of adult zooids increases. Now, when the acti- 

 vating colony of B. gascoi is considered in this connection it is seen that here we have 

 the extreme so far as the length of Periods 1 and 3 is concerned. For in this instance 

 we have Period 1 lasting sixteen days. Even after buds have begun to appear in the 

 colony it may sometimes happen that all the buds degenerate before any open their 

 siphons, thus leaving out the period of adult existence altogether. Usually, however, 

 a few of the buds manage to open their siphons, but frequently close them very soon 

 after.* 



It is seen, then, that when analyzed this difference between the aestivating and 

 normal colony reduces itself to an excessive lengthening of the interval between suc- 

 ceeding generations of adult zooids. The cause of the lengthening seems to be unfa- 

 vorable conditions, either external or internal, for by comparison with two other cases 

 it is seen that when the environment is perfectly normal, and hence probably most 



* It must not be supposed that in these cases the buds have been of no benefit to the colony, for their hearts 

 begin to contract very early, and will thus be of service in helping to maintain the circulation. 



