66 



MANX 



BOTANICAL GAZETTE bAsmax 



- — - 1 a theory of the nucleocentric type, wherein 



the control of development is made to reside within the several cells, 



and specifically within the chromatic matters of the nucleus. Nuclear 



divisions are conceived as being of two types; namely, (i) equating, 



in which the germ-plasm is conserved in its integrity, all characters 



of the mother nucleus being shared equally by the daughter nuclei; 



and (2) differentiating division, in which the daughter nuclei receive 



from the parent nucleus unlike assortments of character-giving bodies. 



All the determinants, capable of giving form to the whole organism, 



being present in the nucleus of the egg, differentiation is concomitant 



with an orderly distribution of the governing bodies, effected in the 



successive nuclear divisions, each different part of the body ultimately 



receiving its proper kind of determinant. 



In view of present limitations of our knowledge, the theory of 

 Weismann is a highly speculative system, and as such has been 



neXTrt t0 mCet u emergendCS ari5in S fr ° m the disco ^ ° f 

 neu tacts. There is perhaps little forensic satisfaction to be gained 



from argument under these conditions. Yet it is undoubted that the 



he proposal of this hypothesis has prompted investigations leading 



to interesting discoveries. And even as a means of tWvW obser- 



,,,,,• . . v,Ui « a means 01 tnrowing ODser- 



IT V S ° me ^ ° f ° rder ' ™y such *eoretic scheme has its 



kinH. fT ,'° mC ' theref0re ' weU WOTth w hile to consider all 

 kinds of facts of ontogenesis in the light of this and other generaliza- 



Irra ved m " ph ° genetics - Th * facts of regeneration have thus been 

 arrayed with relation t^ <i„, r> m. . 



Weismann hypothesis. Regenera- 



tive n h a ~ , *wua- vv eismann Hypothesis. Regenera- 



hole Z TT e ° n ' ^ con ^ence, some new aspects, and the 

 thole subject gains m spirit. A tentative ™J,ri-» i J.HU,«d 



theory 



dnrtmn^ t j -^^iiann ineory nas been the intro- 



los oarts fUnd fT eWal modifi catio n . For the power of reproducing 



pTants tZ " dy P r SSed by animals . and •» *°™ degree by 



unell ' S ",°' aCC ° Un r. ed *" by "" R °-Weismann idea in £ m0 st 



fer m ated i T ° ^ f ° r * is *«%. ** cells, even of dif- 



hose e or, . ' T ead ° f *** de P ri «d of all elements except 



o retain" 1 h", "^ ^ ° f ^ ti ^ > ™ — * ll °« d 

 This auviH detCrmmants efficient for purposes of regeneration. 

 Th,s au.Mhary equ.pment is, however, tightly s , owe d. Under ordi- 



