396 CHIKANOSUKE OGAWA 



Under the binocular, an incision is made into the nasal part of 

 the cornea with a small iridectomy scapel and then the cut is 

 extended horizontally. Flowing off of the aqueous humor can 

 be prevented until the cut is finished by slight pressure of the 

 back of the scapel against the wound; in this way prolapse of 

 the iris is avoided. Compression on the eye causes the lens to 

 slip out easily through the wound. The right eye alone was 

 operated upon. After the operation, the animals were put di- 

 rectly into the water. The wound heals quite easily and the eye 

 recovers its original form. 



For convenience of description, I shall suppose the eye axis to 

 be in sagittal direction. 



RESULTS OF EXPERIMENTS 

 Regular regeneration of the lens 



As already known, the first changes that take place after extir- 

 pation of the lens are depigmentation of the epithelial cells of 

 the dorsal part of the iris and thickening of the upper iris edge, 

 Concerning the point where depigmentation first begins, however, 

 existing statements are not exactly in agreement. According to 

 Wolff and Miiller, ''die innere Lamelle der Iris beginnt ihr Pig- 

 ment zu verlieren, " while Fischelsays "die erste Veranderung 

 besteht darin, dass die Zellen ihres hinteren epithelialen Blattes 

 pigmentarmer werden und die Depigmentation greift auch liber 

 den Pupillarrand hinaus eine Strecke weit auf das vordere Blatt 

 iiber. " Wachs mentions simply that "die Umschlagstelle des 

 ausseren in das innere Blatt entpigmentiert sich;" my observa- 

 tion agrees with this latter statement. The first change, pointed 

 out by Wolff and Miiller, corresponds to a slightly later stage. 



The first depigmentation occurs usually not in the whole upper 

 iris edge, but just in its middle part, only now and then being 

 displaced laterally or medially. Simultaneously with depigmen- 

 tation, or rather prior to it, the iris edge undergoes thickening 

 and presents a club shape if seen in sagittal section. The thick- 

 ening is caused by the splitting open of the two epithelial layers 

 of this part and also by the increase of their height. Mitosis can- 

 not be seen in this stage. Several round cells, richly provided 



