78 Proceedings of Royal Society of Edinburgh. [sess. 
with each other ; hut in the mature dry state they acquire elasticity, 
and tend to become separated from each other, and they thus press 
the seeds through the split ventral surface of the follicle. 
The hairs separating the seeds from the endocarp seem to possess 
the additional function of preventing fracture of the long and brittle 
stalks of the comose appendages, by forming a soft and yielding bed 
for the seeds during their changes of position before they escape 
from the follicle; and they thus insure that the seeds shall be dis- 
seminated with the comose appendages attached to them. 
Drawings and microscopic preparations were exhibited to illus- 
trate the histology of the different parts of the plant. 
A description of the results that had been obtained in the chemical 
and pharmacological examination of Stroplianthus was deferred to a 
future meeting of the Society. 
A New Type of Dimorphism found in certain Anti- 
patharia. By George Brook, Lecturer on Comparative 
Embryology in the University of Edinburgh. 
(Read January 21, 1889.) 
A more or less elaborate system of polymorphism is of frequent 
occurrence in certain groups of colonial Ccelenterata. For example, 
in many Hydroids certain individuals perform the nutritive func- 
tions for the colony, others are specialised for reproductive purposes, 
and so on. The variously modified individuals are connected 
together by a general coenenchyma, which enables the nutriment 
elaborated by the gastrozooids to be utilised by other members of 
the colony. Perhaps some of the most interesting and complex 
cases of polymorphism are to be found amongst the Siphonophora. 
Amongst the Anthozoa dimorphism frequently occurs in certain 
groups of Alcyonaria , but in these cases apparently the speciali- 
sation never results in the formation of reproductive zooids. The 
modified individuals ( Siphonozooids ) differ from those of typical 
structure in the absence of tentacles, the great development of the 
siphonoglyphe, and in other points. They are usually but not in- 
variably sexless, and in certain cases are stated to develop into 
typical zooids. In the Actiniaria the animal is usually solitary; 
