154 ESTIVATION OF BOTRYLLOIDES GASCOI DELLA VALLE. 



for the buds were in the front rank of the growing tissue (Figs. 1, 2, 8, 9), and they 

 were so placed that their anterior, branchial ends looked in the direction of growth; 

 just as these ends do when the young buds push away from the parent zooid by the 

 elongation of the stalk (Figs. 1, 8). 



But the most interesting fact to be noted in connection with this correlation 

 between growth and vigor is that those buds which appeared elsewhere than in the 

 growing region, or which failed to accompany the growing region, always, so far as 

 noted, degenerated considerably sooner than those in the growing region, and were 

 not so liable to be followed by other buds (Figs. 1, 2, 3, 7, 8, 9). Thus, at the top 

 of Figure 1 are represented the outlines of three buds that were not visible on the day 

 before and were not located in the growing region of the colony with the rest of the 

 buds. On the next day these buds had entirely disappeared without reaching even 

 approximately the stage when the siphons open to the exterior. The two circles 

 at the top of Figure 3 mark the place where three days previously there was a col- 

 lection of six buds, some of them quite as large as any in the lower group which later 

 formed the system represented in Figure 3. But this upper group of zooids was not 

 near the growing edge on which the lower group was located, and by August 15 it had 

 entirely degenerated, while the lower group had prospered. Again, in Figures 3 to 

 9, drawn at intervals of one day or less, it can be distinctly seen that even in the same 

 system (Fig. 3) the zooid next the growing edge persisted for at least four days, while 

 the zooids farthest from this edge had already degenerated on the second day. Finally, 

 in Figures 7 to 9 the growing part of the colony with the zooids is represented as 

 extending over the opaque portion of the colony, and the hole (7-) in the latter gives 

 us a stationary point to measure from. Here comparison of the figures shows the 

 direction and rapidity of the growth, and it can be easily seen that the buds that were 

 not in the group at the point of greatest growth failed to develop. 



The comparative prosperity of the buds nearest the growing edge was, I think, 

 due to the larger proportion of nourishment at their disposal. Though it is impossible 

 to prove this, as there is no way of measuring the food in such an animal, several facts 

 point strongly in this direction: first it was on the edge that growth was most consid- 

 erable, not only among the buds but also among the blood-vessels, and growth 

 requires food; secondly, it was there that the greatest vigor was manifested in the 

 ampullar contractions as in other things. Since near the edge the circulation was 

 more vigorous, the blood-supply better, the amount of food carried to the buds by 

 the vessels must have been greater. This matter of the unequal distribution of food 

 throughout the colony and the lack of coordination in the development and disap- 

 pearance of systems will be discussed later. 



