REGENERATION OF THE LENS IN DIEMYCTYLUS 399 



equatorial zone. Owing to this projection, a cavity remains be- 

 tween the lens epithelium and its substance, though later both 

 projection and cavity disappear. This connecting zone is vari- 

 able in its position, deviating anteriorly or posteriorly in different 

 grades from the equator; the position of the lens accordingly is 

 also variable. According to Fischel, ''diei^rtund Weise der Lo- 

 sung dieser Verbindung liisst es zweifellos erscheinen, dass sie 

 lediglich durch das Gewicht der wachsenden Linse erfolgt; hat 

 dieses eine bestimute Grosse erreicht, dann wird die Verbindung 

 gelost." But I think it is most unlikely that separation takes 

 place by the growing weight of the lens, because the lens, after 

 separation from the iris, still remains in contact with the iris in 

 the pupillar region. 



The lens capsule is formed at first on the anterior surface of the 

 lens while the lens is in connection with the iris. 



In normal embryonic development, pigment cells are found 

 sometimes in the cavity of the lens vesicle; the same phenom- 

 enon is seen occasionally also in the regenerating lens. Be- 

 sides the change in the iris epithelium, it is observed now and 

 then that the gold pigment cells in the iris stroma extend to the 

 surface of the lens. 



Time of regeneration 



Concerning the time required for the regeneration of the lens, 

 Fischel ('00) states the following: ^'Ebensowenig glaube ich ther- 

 mische Einfliisse eine Wirkung zusprechen zu konnen. Denn 

 die Begeneration erfolgt im Sommer nicht rasher als im Winter, 

 trotzdem der Temperaturunterschied des Wassers, in dem die 

 Tiere gehalten werden, gewiss kein unbetrachtlicher ist." My 

 results show, on the contrary, that the time required for regenera- 

 tion is different according to the season and individual variety. 

 For instance, thickening in the upper iris edge appears in five days 

 after operation in summer, while it begins in nine days after 

 operation in late autumn. Again, for the first appearance of the 

 lens vesicle, it takes two weeks in summer and more than three 

 weeks in autumn. Since the operated animals were all killed 



