158 ESTIVATION OF BOTRYLLOIDES GASCOI DELLA VALLE. 



favorable, this interval becomes shortest. Just what it is that makes the conditions 

 unfavorable I am unable to say. 



B. Absence op regular generations. — The second difference between the 

 rejuvenating colony and normal ones is that the usual coordination which results in 

 all the zooids of a single generation budding and dying at the same time was lost. 

 There was no longer the former regular succession of generations, and buds and zooids 

 appeared so irregularly that it was frequently impossible to tell to which generation 

 they belonged. 



I will briefly describe the budding of the colony with reference to this point, 

 so that the evidence may be perfectly clear. Thus, on July 15, a few days after the 

 first buds appeared, an inspection of the living colony showed buds in all stages of 

 development, from some whose siphons were open to others which could hardly be 

 distinguished from ampullae. A further examination of sections of part of the colony 

 showed that there were many more smaller buds scattered through the colony. But 

 here, also, great variation in size was observed and no generations of buds could be 

 distinguished. Furthermore, it is quite probable, though I have no direct evidence on 

 the subject, that, as the yellow lobe was present for a week or more before the rest 

 of the colony degenerated, buds from more than one generation of zooids passed into 

 it. All of the first lot of buds that could be seen in life degenerated on July 18 and 

 only part of them were followed by others. The buds, or rather the zooids, that 

 degenerated and were not followed by others probably did produce buds, but these 

 remained dormant. The new buds which appeared (July 20) in the same place 

 where the other zooids disappeared were probably produced by these zooids, and 

 may be spoken of as Generation 2. But Generation 2 had a very short life, having 

 vanished on July 24, leaving only a few very small buds visible. These small buds 

 were probably produced by Generation 2 and may be called Generation 3, but here 

 there is more doubt as to the genetic continuity. The buds of Generation 3 were 

 bunched together. On July 28 they were quite large, and were all in the same stage 

 of development. It looked, at last, as if a good healthy generation had been formed, 

 and the colony was about to resume its wonted aspect. But on the next day, July 

 29 (Fig. 1), three new buds had appeared in another part of the colony, and it was 

 impossible to tell to which generation these newcomers belonged. However, the 

 new buds were not on the growing edge, and had vanished on the next day (July 30). 

 On the same day the young zooids of Generation 3 had rearranged themselves and 

 had formed the first system of the rejuvenating colony (Fig. 2). The next step is 

 again somewhat surprising. Generation 3 disappeared without leaving a trace, and 

 the next buds that appeared were in an entirely different part of the colony. The 



