786 DR. E. B. WILSON ON THE DEVELOPMENT OF RENILLA. 
bolus is at length suddenly passed into the stomach and retained during digestion 
in its upper portion. I was unable to discover any indication of intra-cellular 
digestion. The contents of the veliger shells were dissolved out and were then 
circulated through the gastric cavity in the form of oil globules. The empty shells 
were finally ejected through the cesophagus by a reversed peristaltic action. 
In Leptogorgia, which was fed with oyster larvae, the process was slightly different. 
The larvae were passed into the cesophagus until a large bolus was accumulated at the 
lower end. The bolus was then passed into the stomach and closely clasped by the 
short mesenterial filaments. It was thus held for two or three hours, and its remains 
were finally ejected through the mouth. This seems to indicate that the filaments 
are intimately concerned in the process of digestion; but, as before, I could not 
determine the mode of action of the cells. 
This observation is interesting, taken in connexion with KRUKENBERG’s physiological 
studies upon the nature of the filaments in the Actiniz.* From experiments on 
artificial digestion he is led to conclude that the mesenterial filaments are mainly or 
entirely concerned in the act of digestion—so far, at least, as proteid matters are 
concerned—and my observations seem to point in the same direction. 
§ 15. Arrangement and succession of the sexual polyps. 
I have not succeeded in raising the young colonies in the aquarium beyond the 
stage shown in fig. 178, and my observations on the later stages were made from 
specimens procured in the sand, which were found in every stage of development. 
Hence I cannot give the rate of development, since the young colonies develop very 
slowly or not at all when kept in aquaria. Large numbers of them were examined 
and the succession of the buds was found to be nearly constant in early stages though 
somewhat variable in later ones. 
The buds develop always symmetrically in pairs with wonderful regularity, as the 
accompanying series of figures will show. The appearance of the first pair has already 
been described. 
The second pair invariably appear just behind the first (fig. 182, p*.), and their 
mode of development is quite like that of the first pair. As soon as the dorso-ventral 
axis can be distinguished, they are found to be placed like those of the first pair, 
though the obliquity is less marked, and the axis of the buds often form a right angle 
with the long axis of the primary polyp. The second pair are at first quite 
disconnected from the first pair, but soon fuse to some extent with them, the buds 
being separated by a thin partition wall which terminates by a free edge below 
(fig. 204, e.). The third pair are formed some time after the second, a short distance 
in front of and obliquely below the first. As before, they are at first quite separate 
from the other buds, but soon fuse with the first pair (see figs. 204 to 207). The 
* Vergleichend-physiologische Studien an den Kiisten der Adria, Erste Abtheilung, 1880. 
