418 DR. E. KLEIN. 



me to examine the epidermis -with reference to the pro- 

 cess of division, and we have seen that division of nuclei 

 occurs merely in the deepest or the next following layer. 

 Considering that the superficial layer of cells is shed within 

 five or six days (see the tables on a previous page), we 

 should be justified in expecting to find very abundant 

 division amongst the nuclei of the deeper layer. This, 

 however, is not the case by any means. True, some of 

 the stages of indirect division described on a former page are, 

 according to Flemming and Peremeschko's direct observa- 

 tions, only of very short duration, but I think I can show 

 that all forms of nuclei indicating such divisions — from that 

 of the " convolution " of the mother nucleus to the '^ convolu- 

 tion " of the daughter nucleus — do not represent but a 

 relatively small contingent, not sufficient to account for the 

 copious new-formation of nuclei and cells that must be 

 going on in order to defray such a loss of cells and nuclei 

 as is represented by the shedding of the cuticle within 

 five or six days. I have counted in several fields in a 

 preparation prepared - with picric acid and stained with 

 logwood, all the forms of nuclei indicating indirect division, 

 and I found the following : 



The preparation is a vertical section through the tail of a 

 female adult newt; the thickness of the section is such that 

 the cells of the epidermis lie two deep. The counting was 

 made with the objective E of Zeiss. The size of the field of 

 the microscope under this lens on my stand comprises about 

 30 nuclei of the deepest layer of cells, i. e. the layer next 

 the corium, and as the section is two cells deep, it follows 

 that we may take 60 nuclei as comjirised in the deepest layer 

 of one field. Of course this figure 60 is only approxim.ately 

 correct, since the section is not everywhere of equal thick- 

 ness, and since the nuclei are not everywhere placed equally 

 closely. But I should think the error in accepting that 

 figure cannot be great. As I do not claim any degree of 

 accuracy, we may accept that number as sufiaciently ser- 

 viceable. 



lu Field 1, I count one " wreath ;" one divided, eacli daughter nucleus 



" monaster ;" one " basket." 

 In Field 2, three "convolutious;" one divided, each daughter nucleus 



"basket." 

 In Field 3, one " wreath ;" one " convolution." 

 In Field 4, one " convolution ;" two " baskets;" one divided, each daughter 



nucleus " basket." 

 In Field 5, two " convolutions." 



In Field 6, one divided, each daughter nucleus " basket." 

 In Field 7, one "dyaster." 



