210 SIDNEY F. HAEMER. 



significance of this phenomenon^ which I have frequently 

 observed. 



I am in a position to multiply indefinitely figures showing 

 the important fact that the young larvae are really produced 

 as buds from a "^ primary embryo." I consider that I have the 

 clearest possible evidence of the following statements : 



i. The larvse are produced as buds from an em- 

 bryonic mass of cells found in the young ovicell. 



ii. They are produced in no other way than that 

 mentioned under i. 



The embryogenic organ is invariably present in all ovicells 

 in which young embryos are found, and in most of the older 

 embryo-containing ovicells as well. It is still active, even at 

 the stage shown in fig. 17. The youngest embryos, free in the 

 reticulum, are invariably identical in structure with the ends 

 of the processes of the primary embryo, and there is not the 

 slightest trace in any of the ovicells, young or old, of the de- 

 velopment of larvse by the ordinary process of the segmentation 

 of an egg. 



It might, indeed, be supposed that the bi-nucleated cell 

 shown in the upper part of the reticulum in fig. 11 had the 

 nature of a dividing egg. This supposition is not confirmed 

 by an examination of the actual facts. While the evidence in 

 favour of the origin of the larvae by a process of budding is 

 unmistakably clear, there are no transitions between such 

 cells as the large one shown in fig. 11 and the young two- 

 layered larvae. These large cells, which are normally present 

 in the ovicells, are probably of the nature of '' giant-cells,^' 

 similar to those which are found in developing bone. This 

 subject will be considered later; but it may be pointed out 

 that it is possible that the supposed egg-cell figured by Barrois 

 (1, pi. iii, fig. 1) may have been one of these giant-cells. 



IV. The Development of the Primary Embryo. 

 Fig. 15 (PI. XXIV) is a decalcified internode of C. eburnea, 

 possessing a very young ovicell. The internode consists of 

 one complete zooeciura, which bears the beginning of a lateral 



