144 Transactions of the Society. 



gone this process. Still, it seemed reasonable to snpjiose that any strnc- 

 ture such as statoblasts which floated on the surface must be adapted to 

 this particular possibility ; hence it is reasonable to believe the general 

 correctness of Braem's results, that the fact of statoblasts having been 

 enclosed in ice might have a beneficial effect on their germination in 

 the following spring. It is probably not unlike what happens in a seed 

 or a bulb, which becomes dry, and has to be left in a dormant condition 

 before it is in a position to germinate. 



There is no doubt that statoblasts are structures of the greatest 

 importance for the distribution of the species. Streams would naturally 

 wash the statoblasts towards the sea, and this could be counteracted by 

 statoblasts being brought into the upper reaches of the river. That 

 was a point on which further evidence was needed. There were one or 

 two isolated records of statoblasts having been recovered from the mud 

 attached to the legs, feet and beaks of aquatic birds ; and all such 

 records were of interest, and should be carefully preserved. This seemed 

 one of the most probalile ways in which a new place could be colonized 

 with statoblasts. 



There was a further point to which he would like to draw the special 

 attention of Fellows. Fresh-water Polyzoa were, as far as he knew, 

 unique in respect of the number of their reproductive processes. It was 

 common in the animal kingdom to find two different methods of re- 

 production occurring : one the sexual method, by fertilized eggs ; and 

 the other the asexual method. And there were many cases in which 

 there was a distinct alternation of generations, such as the Hydrozoa, 

 by eggs and by budding. As a general rule, budding resulted in an 

 increase in the number of individuals of a colony, but not in the pro- 

 duction of a new colony. In fresh-water Polyzoa one found a remarkable 

 phenomenon. Mr. Rousselet said that some of the Polyzoa produced 

 ciliated larvae; and he thought that gentleman might have made the 

 statement general. In addition, there was the asexual production of 

 statoblasts taking place simultaneously with the production of other 

 buds which increased the number of individuals of the colony. These 

 statoblasts, when they germinated, also gave rise to new colonies. 



There was one further complication, namely, that there were two 

 distinct kinds of statoblasts : ordinary statoblasts, which had a ring of 

 air-cells enabling them to float: and sessile statoblasts (without the ring), 

 which were produced at the base of the colony, and remained adherent 

 to the substratum on which the colony had been growing when the 

 colony disintegrated in the autumn. So there were three distinct kinds 

 of reproductive body : ovum, ordinary summer statoblasts, and winter 

 statoblasts. One of the things about which one would like more infor- 

 mation was, What was the relationship between these various reproductive 

 bodies ? Was there any difference between the colonies which were 

 produced by the fertilized ovum, and those which were produced by 

 statoblasts ? Also, was there any difference between colonies produced 

 from sessile statoblasts, and those produced from floating statoblasts ? 

 It seemed to him that this was a subject which would well repay careful 

 experimental work ; and he did not think the difficulty of the investiga- 

 tion would prove at all insuperable. It would be possible to isolate 

 particular statoblasts, and to expose them to conditions of various kinds. 



