2 University of California Publications in Zoology. VaL - c 



course in which Professor C. S. Minot has followed it with such 

 illumination, it has seemed to me that significant information 

 might be obtained from weighing the same egg or a known num- 

 ber of eggs at different stages of development beginning with the 

 earliest. It is probably always taken for granted that such eggs 

 dimmish in weight up to the time when extraneous food begins 

 to be taken by the embryo. The well-known fact that the early 

 growth processes are like physiological processes in the stricter 

 sense, accompanied by a production of carbon dioxide, has, it 

 would seem, generally been regarded as all the proof necessary 

 to that effect. Since the loss from this source can tell nothing 

 about the nitrogenous loss, this method of recognizing diminution 

 in weight is inadequate for establishing quantitative relations be- 

 tween the total loss and rate of loss during a definite period of 

 development. 



I asked Mr. S. E. Bailey to see what he could do with the 

 problem while at the San Diego Marine Station this last summer. 

 The experiments are described in Mr. Bailey's own words. The 

 results are meager since the time that could be devoted to the 

 study was short. They are published not because they are re- 

 garded as of much value of themselves, but rather to show the 

 practicability of such determinations aud to give opportunity for 

 a few reflections on the possible significance of this kind of in- 

 vestigations. These reflections I put in the form of questions. 



Supposing the results obtained, namely, that eggs do diminish 

 in weight from the very beginning of segmentation to the time 

 when extraneous food is taken, to be correct, the following queries 

 arise : 



1. Since part of the loss is undoubtedly due to the consump- 

 tion of energy in segmentation, is there reason to assume that any 

 members of the egg-complex that divide automatically, e.g., 

 nucleus, chromosomes, centrosome, etc., do not share in the loss? 



2. Is there reason to assume that any portion whatsoever of 

 the egg in which the metabolic processes are going on, i.e., any 

 portion that can be counted as living, is exempt from a share in 

 the loss? 



3. If there is no good ground for making either of these as- 

 sumptions, what becomes of the conception of a germ-plasm or 



