870 THE AMERICA N NA TUB A LIS T. [ Vol . XXXV III. 



Some observations exceptional to this law may be briefly cited. 

 Frenzel ('85) found in the intestine of certain decapods that the 

 epithelium is regenerated from basal cells which show all stages 

 of amitosis, while in other closely related genera the growth is 

 from mitotic nuclei. Wheeler ('89) found that in the early blas- 

 toderm of Blatta all the nuclei divide _ amitotically at a certain 

 sta-e, and that this is followed later by mitosis. Goppert ('91) 

 lound amitosis in the leucocytes of the salamander's liver which 

 he regards as regenerative. Verson ('91) found that in the 

 testis of the silkworm single large nuclei divide amitotically 

 while their daughter cells give rise to spermatocytes mitotically. 

 Aleves ('91) found that in the salamander certain of the cells of 

 the tesiis divided arnil ot ieallv in winter and mitotically in .sum- 

 mer. IVeus>e found mitosis in the youngest egg compart- 

 ments of the ovaries of hemiptera, which consist of only a few 

 eeils and wheie active cell multiplication must be taking place. 

 I In.s w l iter t-iies obserx ations of Carnoy and Claus in support of 

 liis claim that amitosis is regenerative in some cases. Pfeffcr 

 ( ()9. Wil.son, :oo) found that if " spirogyra be placed in water 

 containing 0.5 -[ .00 yr of ether active growth and division con- 

 tinue, but only by amitosis. If, however, the same individuals 

 be replaced in water mitotic division is resumed and an entirely 

 normal growth continues." 



These various observations upon amitosis all indicate a close 

 relation between amitosis and mitosis. 'I'he fact that nuclei 

 'livide in one wav in winter and in the other in summer, that in 

 one geiuis one method pievails and in another related genus the 

 "^'i^'"'. 'I'ui that nuto.si. can be replaced in the same cell by ami- 

 tosis under the inituence ot etlier. all of them suggest a process 

 ^it l)ottom tlie same but .operating dilTerently under the influence 

 "t ditterent circumstances. li so. we should regard amitosis as 

 the nioie piinntixe mode and mitosis as a more highly special- 

 ized mnde deriN.-d tn.m it. .And we need n<.t then be surprised 

 It the moiv prinutive mode sh..uld occasionallv <.ccur in a place 

 principle, ue .should look for the more highly 

 - ■■ 'rh-iiL;-h we .generally fmd cell multiplication to 

 •Aith mitosis and special metabolic activity to be 

 ^' ^mutosis. we might in si)ecial cases find that cells 



