A STATISTICAL STUDY OF MITOSIS AND AMITOSIS. 237 



olism were very intense, and the swallowed yolk were very 

 quickly used up, instead of remaining in the digestive tract for 

 five or six weeks as it actually does, the elimination of waste 

 products might be rapid and great enough to bring about an 

 actual decrease in the size of the later stages. Such shrinkage 

 would indeed occur were the effects of the digestion of yolk and 

 of the elimination of wastes not more than compensated for by 

 four factors, three of which obtain in every individual, whereas 

 the fourth is operative only in the majority of cases. In the first 

 place, after the period of cannibalism, the larvae actually increase 

 in size by ordinary growth ; in the second place, even after com- 

 pletely filled with eggs, they continue to inflate themselves with 

 the albuminous material in which they float ; and thirdly several 

 days after ingestion many of the eggs lose their pellicles, and 

 since the yolk granules are large, very firm, and vary consider- 

 ably both in size and shape it is to be expected that they 

 would take up more room than when neatly packed, as they are, 

 in the intact ova. In addition to these factors of enlargement, 

 one very remarkable one operates in so many cases, that it may 

 be called a matter of common occurrence. In every capsule, 

 practically, some of the cannibals in stage III. burst, and in those 

 egg-cases in which only two or three larvae in later stages are 

 found, the majority of cannibals have broken. In these instances 

 the surviving larvae are invariably larger than those in the more 

 populous capsules. Experiments have shown that a fully gorged 

 cannibal, which under other conditions would have ingested no 

 more eggs, will double the number it contains if the food supply 

 is increased. From these experiments, as well as from the obser- 

 vation that where embryos are below the average in number they 

 are above the average in size, and the further observation that 

 bursting accidents occur in practically every capsule, it follows 

 that after the stretching which transforms stage I. into stage III. 

 has occurred, a further increase in size depending upon the fac- 

 tors mentioned takes place. 



During the particular period of development now under con- 

 sideration the activities of the entoderm are such that in spite of 

 the stretching due to all of the causes mentioned, the cells of the 

 inner layer change from the spindle-shape to the cuboidal. The 



