No. 2.] THE OVARIAN EGG OF LIMULUS. 141 



else coincides with it. So far as I have been able to determine 

 from an examination of many specimens throughout the grow- 

 ing series, the number of diverticula that appear in a cross 

 section of a tube is equal to, and does not exceed the num- 

 ber of oogonia in the cross section of a tube previous to the 

 formation of an oocyte. 



Furthermore, in the adult animal having empty follicles, 

 the number of eggs in cross section of a tube decreases in 

 proportion as the empty follicles increase ; and the size of the 

 smallest eggs is proportional to the number of empty follicles, 

 and inversely proportional to the number of eggs in cross 

 section. 



In higher animals it is known that a period exists when eggs 

 for the first time are discharged. It is also known that a 

 period exists after which reproduction does not take place. It 

 is also known that in many higher animals it is impossible to 

 find the earliest stages of the egg in the adult animal, and it 

 frequently has been assumed, on this account, that not only 

 the origin, but the history of the egg in the adult differs radi- 

 cally from the history of the egg of the same animal in its 

 early stages. Thus Balfour ('78), in Elasmobranchs, describes 

 two methods by which the egg may arise : first, by a fusion of 

 a number of cells, which he thinks is the normal process ; and, 

 second, by a gradual transformation of a primitive ovum into a 

 permanent ovum. 



To enumerate, briefly, the observations : In the young 

 animal, up to five inches, the germ cells form the lining of the 

 ovarian tube. At this period growing oocytes make their 

 appearance as diverticula, and continue to be formed up to the 

 period of sexual maturity. After this period no new oocytes 

 are formed ; but those already existing continue to grow as the 

 animal grows, until the period of sexual maturity, when the 

 eggs in the follicles first formed are discharged into the ovarian 

 tube. The first oviposition takes place considerably later, and 

 continues at intervals till all the eggs have been matured, 

 which may cover a period of at least eight years. With an 

 intermission of more than one year between the periods of 

 oviposition, as seems probable from the observations recorded 



