6o 



botanical gazette. [ March, 



can form the basis of a new being. The productions of gall- 

 insects show in the same manner that in every part of a plant 

 many hereditary characters lie hidden, which will only ap- 

 pear if a proper stimulant is applied. Thus the hypothesis 

 of germ- and somatic-plasma, though it may have a logical 

 foundation in Weismann's assumption of ancestral plasmata, 

 is not at all supported by the facts observed in nature. And 

 irom this point of view it certainly is a great advantage that 

 pangenesis has nothing whatever to do with such a second- 

 ary hypothesis. 



Lastly, Spencer and Weismann both admit that when 

 sexual propagation takes place, the physiological units or 

 ancestral plasmata of father and mother are both to be found 

 in the offspring. And this would lead to the assumption 

 that in every organism all its ancestors from the beginning 

 of organic life till the present day are represented. Both 

 naturalists have felt the absurdity of such a proposition, and 

 both are compelled to a new auxiliary hypothesis ; Spencer 

 supposing that diss milar physiological units, when mixed to- 

 gether, tend to segregate, and Weismann taking for granted 

 that each time, before a sexual union takes place, one-half 

 of the ancestral plasmata are first removed, so that their 

 number remains constant. This removal, according to Weis- 

 mann. takes place when the second polar-globule is expelled 



from the ovum. 



Pangenesis, again, has no need whatever of such an as- 

 sumption, as no reason can be given why an excessive num- 

 ber of different pangens should associate. 



From all these considerations it may be concluded with 

 safety that pangenesis, combining all advantages of its sister- 

 hypotheses, greatly excels them, so that it has no need of 

 any auxiliary hypothesis whatever. 



It is, moreover, much more simple in its application. Ap- 

 parently this 1S not the case, as pangenesis assumes the ex- 

 istence of great numbers of different pangens in everv being- 

 whilst of ancestral plasmata or phvsiological units one kind 

 suffices for the formation of the most complex organism 

 If, however, not a single being, but all organisms which the 

 world contains are considered, the case is entirely reversed 

 1 hen it must be conceded that one is compelled t6 assume as 

 many different kinds of phvsiological units or ancestral plas- 

 mata as there are and ever have been species in the world 

 in pangenesis, however, a relatively small number of differ" 

 ent pangens will suffice to form by its numberless combina- 



