ALCYONIUM. 113 



nucleated syncytium undifferentiated into 

 endoderm cells. 



Fig. 19. A section through a ventral mesentery in the 

 summer, showing the manner in which ova 

 are formed, a. A clump of endoderm cells 

 sinking below the surface. h. A nest of 

 young egg-mother cells, c. A stage in which 

 the protoplasm of the cells composing a nest 

 has fused into a single mass, and the number of 

 i. nuclei is reduced considerably, d. Last stage 

 in which only one nucleus, the germinal 

 vesicle of the ovum, remains and the ovum 

 has begun to increase in size. The retractor 

 muscles R. Msc. of the mesentery are here 

 seen in transverse section. 



Fig. 20. Transverse section of an anthocodia in the 

 region of the gonads, showing the six mesen- 

 teries bearing ova and the two (dorsal) mesen- 

 teries which are barren, Dmf '. 



Figs. 21, 22, 2-°>. Three types of spicules met with in 

 Alcyonium. 



Fig. 24. The youngest stage of colony formation that 

 has been found bv the author. 



