GRANTIA. 23 



Ova and sperm are formed by the same individual, and the 

 animal is therefore hermaphroditic, but the products ripen at 

 different periods and are seldom both present in an individual 

 at the same time. 



7/ the time allows, draw ova, sperm-spheres, segmenting eggs, 

 and embryos. 



It is desirable to examine specimens of Leucosolenia, a still 

 simpler sponge, and of some of the more complicated forms, 

 hke commercial sponges, Spongilla, Cliona, and Chalina. Why- 

 is more than a single osculum desirable in such forms? Under- 

 stand the relation of the internal structure of the complicated 

 forms to the more simple forms. What reason is there for the 

 complication? 



The individual cells of sponges may be separated by squeez- 

 ing through fine silk bolting cloth. Such cells will come to- 

 gether in a dish of sea-water to form aggregates that will develop 

 into new sponges. (See Wilson, loc cit.) 



