No. 2.] THE OVARIAN EGG OF LIMULUS. 145 



inches long may not be discharged for many years thereafter, 

 even though the difference between the two in point of time 

 of first appearance may be much less. 



It is known that in many higher animals, especially in the 

 human subject, precocious growth is often accompanied with 

 precocious sexual maturity, and that this marks an important 

 epoch in the life of the individual. It is known also that this 

 period is evidence of maturity of the sexual organs. In Limulus 

 it seems extremely probable that the discharge of the first egg 

 into the ovarian tube marks the period after which no new eggs 

 are formed. Those already formed continue to grow at the 

 decreasing rate at which the animal increases in size, after the 

 period of sexual maturity. They are discharged from the follicle 

 when they attain to the size which is normal to them ; and, 

 continuing thus to be discharged and no new eggs being 

 formed, the time of sterility finally arrives. 



On the discharge of the egg from the follicle into the ovarian 

 tube, it is severed from its organic connection with the parent 

 organism and acquires a new environment. Here the egg 

 increases to double its former size within a very short period 

 of time. As will appear later, this change in environment and 

 in the rate of growth is accompanied by marked internal changes 

 in the constitution of the yolk. The important fact to note 

 here is that with the severance of the egg from its organic con- 

 nection with the parent organism the correlation in growth no 

 longer exists ; and that the egg, having acquired an individual 

 existence, grows at a rate entirely out of proportion to the rate 

 of growth of the animal. 



The egg now is surrounded on all sides by the secretion of 

 the epithelial cells; it no doubt utilizes this secretion as nutri- 

 ment. In studying the structure of the egg, it appears that the 

 egg membrane is radially striated, and that these radial striae 

 are due to protoplasmic fibers that extend out to the investing 

 tunica propria and are in some way connected with it. When 

 the egg is discharged it becomes separated from the tunica 

 propria. This remains behind as the only wall at that point of 

 the tube, and later becomes lined with a new epithelium, per- 

 haps regenerated from the surrounding epithelial cells. The 



