1889.] BOTANICAL GAZETTE. 59 



may be blended together in the same individual, even if they 

 originally belonged to different species. This is most clearly 

 shown by the occurrence of hybrids, which generally hold 

 an intermediate place between the father and mother. But 

 even in this case the characters retain their independence, as 

 is clearly shown when these hybrids are fertile inter se. For 

 in the subsequent generation generally some individuals 

 wholly revert to the shape of their grandmother, others to 

 that of their grandfather, and all intermediate gradations 

 may be observed. In normal sexual reproduction in general 

 the same rules prevail. All the foregoing facts, of which I 

 am only able to give a brief summary, point to the conclusion 

 that every character is bound to its own kind of material 

 particles, and that these are in many respects independent 

 of each other. On the other hand, it will be very difficult, if 

 not impossible, to reconcile with these facts the view that in 

 living beings all hereditary characters of the species are rep- 

 resented together by one and the same kind of indivisible 

 particles. At all events this view is a wholly superfluous 



auxiliary hvpothesis. 



But there is more. When the different organs of the body 

 are formed and developed, the characters of these organs 

 gradually appear, and thus some parts become different from 

 others. In pangenesis this offers no difficulty, as it is not 

 inconceivable that some pangens are developed in one, some 

 in another part of the body. But if the opposite assumption 

 is made, we here meet with many obstacles. This subject has 

 been discussed bv Weismann, and he has been forced to the 

 supposition that there are two strictly separate kinds of pro- 

 toplasm, one of which he has called " germ-plasma" (Keim- 

 plasma), the other «« somatic plasma " (somatisches Plasma). 

 The first of these consists of his "ancestral plasmata," and 

 can reproduce the whole organism. Somatic plasma is devel- 

 oped from germ-plasma, when the vegetative organs ot the 

 body appear. It is less complex in structure, and contains 

 only those characters which are needful for the parts to be 



formed. 



In the higher orders of animals it may seem in some de- 

 gree possible that two such kinds of protoplasm should exist, 

 but every botanist will grant that in plants there is an over- 

 whelming evidence against the supposition that the proto- 

 plasts of leaves and roots are widely different from those of 

 spores and seeds. Many are the cases in which well-defined 

 vegetative organs and even all cells of highly complex plants 



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