Objections to W eismann : Position 315 



many plants which are able to reproduce themselves com- 

 pletely from only a fragment of a specialized organ. The 

 many varieties of the common house plant begonia regen- 

 erate very rapidly from a bit of stem or leaf (Fig. 85) . A 

 plant thus grown from a bit of the vegetative body eventu- 

 ally produces flowers with effective sperms or eggs — that 

 is to say, germ plasm seefus to be produced front specialized 

 soma material. In earthworms and other comparatively 

 simple animals an an- 

 alogous situation may 

 arise. These animals 

 can regenerate a com- 

 plete individual from a 

 portion of the body. 

 The regenerated indi- 

 vidual may then bear 

 functional ovaries or 

 spermaries. 



A second objection F'°- ^^- Regeneration in Plants 



cornes from the observed " ^ '"f- °' "™ ' p,°"'°" °\ ' '"/ °^ 



. - . bryophyllum or begonia be placed on damp 



unity Oi tne organism. earth or sand, tiny roots will form at certain 



Each organ is influenced Po^"" ^^^"S the border; buds will be produced 



, L U ^^^ after a while there will be one to several 



Dy Wnat nappenS to complete plants which may grow into mature 



every other organ. ^We individuals. From Gruenberg, Biology and 



L- t A 1-Vi 1- l-V» Human Life, published by Ginn & Company. 



hormones discharged by the organs of internal secretion 

 produce profound effects in . remote parts of the body. 

 It is difficult for us to believe that the germ remains un- 

 affected by what happens to the body. It is at least as 

 inconceivable that the germ cells should escape such in- 

 fluences as it is that bodily changes should modify the 

 germ cells. 



The Weismann objection to Lamarckism is nevertheless 

 on the whole sound. Recent discoveries regarding the 

 mechanism of inheritance, especially the relation of the 

 chromosomes to the transmission of particular characters, go 

 far to support the essential features of Weismann's theory. 



