3IO A. RICHARDS. 



several writers that mitosis may follow amitosis are to be noted in 

 which they cite cases of direct division in the maturation and pre- 

 maturation stages of various forms. To meet these claims we 

 shall doubtless have to revise somewhat our ideas of the mean- 

 ing of amitosis, but at present the progress toward such a re- 

 vision seems to have overstepped the bounds of conservatism. 



Among the older workers on this line are Meves, Preusse, 

 and Pfeffer. Meves found amitosis to occur in the early stages 

 of spermatozoon formation in Salamandra in the autumn followed 

 by mitosis in the spring, but some of these cells have since been 

 shown to take no part in the formation of spermatozoa. Preusse's 

 work has been much quoted in this connection. He found 

 amitosis in the ovaries of Hemiptera. However, a reinvestigation 

 of this case by Gross in 1901 served to bring it under the theory 

 of Ziegler and vom Rath. Gross showed that this method of 

 cell division did occur but much less widely than described by 

 Preusse. Its occurrence is restricted to two kinds of cells, 

 degenerating and secretory ; this, of course, proved that he 

 was dealing with a special case under the old theory. Pfeffer's 

 work on Spirogyra has been discredited by Nathansohn ; in fact, 

 opinion among botanists is decidedly adverse to the view that 

 amitosis may be followed by mitosis in a single nucleus. This 

 opinion is expressed by Strasburger in his recent summary of the 

 individuality question. 



Working on the spermatogenesis of the sparrow in 1900, 

 Loisel saw nuclei which began division by amitosis and later con- 

 tinued by indirect division. He says that the amitosis was not a 

 sign of degeneration ; but again, he shows that the greater part 

 of certain spermatocytes and spermatids degenerates. To reach 

 a safe conclusion in this case one must needs know the relation 

 between amitosis in the sex cells and degeneration in the sex 

 products. Degeneration on the part of spermatozoa in the 

 Hemiptera has been traced by Morgan and by Miss Stevens to 

 the absence of a single chromosome. If cells lacking a single 

 chromosome degenerate, certainly one would expect degenera- 

 tion in cases where part of the sex cells had previously divided 

 by as indifferent a method as amitosis seems to be. 



Especial importance has been attached to cases of amitosis in 



