144 O. C. GLASEK. 



near this average contained by actual count over 300 eggs. 

 Some larvae of larger size undoubtedly contain more eggs, and 

 some are entirely devoid of them. 



What regulates the number of eggs swallowed? As already 

 noted, eggs in all stages of segmentation may occur in the same 

 capsule. Similarly in older capsules larvae of very different de- 

 grees of development may occur together. Of these the most 

 advanced, the first to be ready to swallow, gets most of the eggs, 

 while its tardy mess-mates must take what remains. Those 

 that are very late in reaching the point where they can ingest 

 eggs often get none at all. They remain dwarfed and subsist 

 on the jelly as best they can. Most of these dwarfed larvae de- 

 generate or are ingested by the cannibals, but occasionally some 

 hatch as " runts " which are normal in all respects except size. 



Of the larvae which develop at a uniform rate those which have 

 the most distensible mouths and the most violent ciliary action 

 in the adoral field get more eggs than those with less distensible 

 mouths and a less active ciliary mechanism. Thus in general, 

 the number of eggs which a given larva secures depends on how 

 early it enters the period of cannibalism and how rapidly and 

 easily it swallows. 



Repeated experiments were tried to find out the effect of arti- 

 ficially increasing the food supply of a given larva. One of these 

 experiments gave a very remarkable result. 



I w r as not able to keep the larvae in a healthy condition outside 

 of the egg cases, nor to satisfactorily reseal a capsule once opened. 

 The problem of artificially increasing the food supply of a given 

 embryo offered some difficulties until I tried the plan of injuring 

 some of the larva? inside of a capsule. This can be done easily 

 by allowing them to drift into a corner of the egg case, holding 

 them there by pressure on the rest of the capsule and then com- 

 pressing them with a pair of strong forceps. With care one or 

 two larvae can be kept out of the corner, and all those which have 

 been coralled can be injured in the manner described. 



An injury to the excessively thin body-wall has the same effect 

 as a hole in a bag of grain. The eggs which have been swal- 

 lowed roll out and leave an empty membrane behind. In this 

 way a thousand eggs, which have been swallowed once, may be 



