298 A. FRANKLIN SHULL 



intestine, and is believed to absorb or ingest the material for its 

 growth from one or both of these organs. If any somatic cells 

 exhibit changes in the Kernplasmarelation in relation to the life- 

 cycle, it seems likely that they are the cells of the yolk gland and 

 stomach-intestine . 



METHOD OF MEASUREMENT AND PRECAUTIONS IN STUDY OF 

 KERN PLASMA RELATION 



The general method of determining the Kernplasmarelation 

 was to make drawings of the sections of the cells, measure the areas 

 of the nucleus and cytosome in these drawings, and divide the 

 nuclear area by the cytosomal area. This method does not, of 

 course, determine the actual volume of either nucleus or cytosome. 

 It does not determine even the relative volume of nucleus and 

 cytosome. If, however, in two cells of the same shape, one has a 

 relatively greater nucleus than the other, the drawing of a section 

 of the former will also have greater relative nuclear area than will 

 the latter. That is, any increase in the actual Kernplasmarela- 

 tion will be shown by an increase in the relative nuclear area in 

 the drawing of a section ; but the two increases will not be equal. 

 Since we are nowhere interested in the absolute value of the Kern- 

 plasmarelation, but only in whether there is an increase or de- 

 crease ; since we require only to know whether the Kernplasmare- 

 lation in one lot of animals is greater or smaller than in another 

 lot, but not how much greater or smaller, the method described 

 seems adequate. 



Oocytes. Drawings of the oocytes were made with the aid of 

 a camera lucida and Avere then enlarged photographically. Only 

 those oocytes were used which had undergone sufficient growth to 

 be easily drawn with accuracy. None that had reached full size 

 and were about to produce the first maturation spindle were 

 dra;Wn, for at that time the nucleus grows rapidly, so that great 

 variability in the Kernplasmarelation would have been intro- 

 duced. The stage during which this nuclear growth occurs can 

 be easily recognized, since the egg is nearly fixed in shape, and 

 appears in the sections in the form of a regular ellipse or circle, 

 whereas the younger oocytes, which are still elastic, are distorted 



