Protandry and Senescence in Corals. 471 
Remembering the occurrence of a ciliated larva in the Madre- 
poraria, it is impossible to believe that the colonies of a single 
species in any area are of the same age, and they certainly are 
not of the same size, hence have not a like number of polyps. 
It is consequently necessary to suppose that in an area — owing 
probably to some change in the physical conditions of their 
environment — all the corals of some single species have been 
stimulated to ripen and dehisce their generative products at the 
same time, the act leading ultimately to their weakening and 
death. As the colonies in the cases especially examined were 
female there may be protandry. 
The above explanation is neither complete nor quite satisfac- 
tory, but it is clearly evident that there is here an entirely different 
phenomenon to senescence. The only close parallel is that of 
the larger species of bamboo, in which death follows the act of 
flowering. Every plant of the commercial species in a district 
produces its fructification at the same time and dies. As wide- 
spread inconvenience commonly results in India, China and 
Burmah, the circumstance is of common knowledge. There are 
no definite experiments to show whether the offshoots of bamboos 
of different ages ab ovo fructify at the same time. It is, however, 
almost certain that in the country of an intelligent people they 
must do so, or else they would be largely exported from district 
to district. The cause' in bamboos must be sought in some change 
of season, and hence there is almost a complete parallel with 
the above-mentioned colonial corals. The whole phenomenon is 
obscure, but the circumstances show that there is a phenomenon, 
which requires — and would almost certainly repay — special in- 
vestigation 1 . 
The consideration of the above phenomenon arose naturally 
% out of my investigation of the anatomy of Flabellum. It is yet 
only right to mention that my friend, Mr R. C. Punnett, had 
more particularly drawn my attention to the question of senes- 
cence in general. 
1 I would express my thanks to Prof. Marshall Ward for references to the 
phenomenon of the fructification and death of bamboos. These merely show that 
there are no definite experiments. For the facts I have relied on Mr Willis’ and 
other information, which I collected in India and Ceylon. 
I have discussed the question of senescence in invertebrates with several 
zoologists. Mr Bles has mentioned to me the case of an Alcyonium, but un- 
fortunately no account of it has, so far as I am aware, been published. 
