METHOD OF CELL DIVISION IN MONIEZIA. 295 



III. CONCLUSION. 



My examination of Richards's material has only confirmed 

 me in my conclusion that direct division plays an important 

 part in the developmental cycle of Moniczia. in the germ cell- 

 as well as in the soma. I believe I ha\t- at least shown clearly 

 enough that this material contains something besides negative 

 c\ idence fur amitosis. 



We are, I think, ii"t yet acquainted with the nucleus as a 

 dynamic system. We know something of ii morphologically 

 and almo-t all our hypothe-e- .uid theories c< mcernitiL; il are 

 ba-ed on the morphological data obtained from lixed material. 



I'm e\cn \\hen we <oii-ider only the re-ult- of direct obser- 

 vation ii is difficult to under-taiid ho\\ cytologists can continue 



as many do in ignore or minimi/e the importance of the rapidlv 

 iin rea-inv; number of o|.-er\ation- mi tin- 'ivmTeiici- nf direct 

 di\i-ion. ( Vrtainlv tin- \\ork of recent years on proto/oa, to 

 mention only tin-, ^roiip. ha- brought to li-ht many apparent 

 facts \\ hich are not in agreement \\ iih current cytological theory. 

 \\heie there i- SO much ^nmke it \\<nild -eein that there mu^t be 

 Collie tin . 



Moreover, uhen \\. -d the micleii- as a (Kn.unic s\-tem 



rather than a UK >rph"l< njcal ^trudure the nece^-it\- for a^> 

 the indi\ idualil\ <>r contimiii\ of the chromo-ome- 

 eiitireK. The reappearance o| a <letmite and coil-taut number 

 ol chroino-i.iiH-, in successive i-ell -eiirratioii-- i- e--ein ially the 

 >ame problem a^ the reappearance <.f ti\e tinker- on the hand 

 in successive -.< in ration^ of man, <>r any other case "f the in- 

 heritano oi organs or pan- in definite con-taut number yel ue 

 do not regard it .1- necessary to a--ume that the-e fin^ei- .it- 

 part- maintain their indi\ idualit \ at all Stages of the life cycle. 

 Instead of bein- tile ba-i^ of heredity the chronio-ome i< it -elf 

 a problem in hereditx. The theory ! -o-ealled chr nno-ome 

 indi\ idualit\ i- a \\holly nime<(--ai\ hvpothe-i- and a hea\ \ 

 burden for cytolog) I" c.inx. -ince it i- imt in accord \\ith (he 

 fact'- and require- -upplemcntarv h\pothe-e- at every ]>oint. 



There i- e\ t r\ reason to belie\e that the nucleii-. like other 

 dynamic -\-lem-. \\ ill beha\ e differeiilK under difh-rent internal 

 and external condition-. What omceixable rea-oii i- there 



