STRUCTURE OF THE LAEVA OP SPONGILLA LACUSTBIS. 447 



When the sponge again expanded on being supplied with fresh 

 water the larvse came out, but owiug to their detention inside 

 the mother colony many of them had used almost all their 

 food material, and were so far abnormal. It is highly probable, 

 however, that had they been preserved in some other fixing 

 reagent than absolute alcohol Prof. Delage would have found 

 the granules in question, though less numerous and reduced 

 in size. 



Another detail of Prof. Delage's account, with which I 

 cannot agree, is that the flagellated cells are actually taken 

 in by the amoeboid cells. After the most careful consideration 

 of the point in question I am of opinion that they are plas- 

 tered to the surfaces of the amoeboid cells rather than enclosed 

 by them. If Delage's view were correct we should not expect 

 to be able to see the outlines of the flagellated cells after they 

 had entered these associations, but they are easily made out 

 for some time, as can be seen from fig. 29 h. Delage was led 

 to this view by the presence of the yolk bodies, which he did 

 not distinguish as such, and which are undoubtedly inside the 

 cells with vesicular nuclei which occupy the centre of the 

 groups. 



It appears, therefore, that owing to his failure to detect the 

 yolk bodies in the larva Delage concluded that all the small 

 bodies in the " polynuclear groups '' were nuclei ; and further, 

 owing to the presence of true yolk bodies inside the cells, and 

 his failure to detect the outlines of the flagellated cells soon 

 after they had entered the groups, he came to the additional 

 conclusion that the small nuclei were inside the central 

 cell. The fact is that these aggregations contain both yolk 

 bodies inside the central cells, and the small nuclei of the 

 flagellated cells plastered to their surfaces. 



The last view with which wehave todealisthatof Noldeke(13). 

 The peculiarity of this view is that it involves as a consequence, 

 like that of Gotte (5), the formation of the whole sponge from 

 the inner mass, or so-called " endoderm " of certain authors. 

 Noldeke's observations seem to be far too limited to enable 

 anyone to come to such drastic conclusions. He seems never 



