EFFECTS OF RAYS OF RADIUM ON PROTOPLASM 



329 



for the eggs do not tend to stick together as in the controls. In 

 a few minutes the vitelline membrane is pushed away from the 

 surface of the egg so that the perivitelline space increases in 

 width. Figure 1, which was drawn from the living egg just be- 

 fore the first cleavage, shows the extent to which this increase 

 may occur. The walls of the alveoli are drawn out so that they 

 extend from the egg protoplasm up to the delicate plasma 

 membrane which lies just beneath the vitelline membrane. The 

 following measurements taken from many living eggs just 

 before the first cleavage and 16 hours after show the extent of 

 this increase in width: 



Through the kindness of Dr. G. L. Kite who dissected a num- 

 ber of eggs from the same lot from which these measurements 

 were taken, I was able to observe that the physical properties 

 of the protoplasm and of the egg membranes are greatly altered. 

 The membranes are still sufficiently tough to hold together when 

 the dissecting needle is pressed against them, but they are softer 

 than normal and can be punctured without difficulty. The 

 protoplasm, instead of being a fairly firm gel is soft, and flows 

 freely through a small tear in the membranes. The perivitel- 

 line space is filled with a semi-gelatinous substance which stains 

 with various protoplasmic dyes. The fact that this is more 

 fluid than the normal jelly may indicate that it is a mixture of 

 jelly and wlater. Certainly not all of the jelly is given off after 

 insemination. The treatment with the beta rays has so altered 

 the membranes that they are no longer able to allow the jelly 

 to pass through them in a normal fashion. According to Dr. 



