348 



APPENDIX 



single cell, which is capable by assimilation and formation of new 

 cells to become an independent organism. This development fol- 

 lows a constant law, which is founded on the material composition 

 and arrangement of the elements which meet in the cell in a vivify- 

 ing miion. If the reproductive cells be of the same kind and agree 

 with the foundation cell [fertilised ovum] of the mother plant, then 

 the development of the new individual will follow the same law 

 which rules the mother plant. If it chance that an egg cell unites 

 with a dissimilar pollen cell, we must then assume that between 

 those elements of both cells, which determine opposite characters, 

 some sort of compromise is effected. The resulting compound cell 

 becomes the foundation of the hybrid organism, the development 

 of which necessarily follows a different scheme from that obtaining 

 in each of the two original species. If the compromise be taken to 

 be a complete one, in the sense, namely, that the hybrid embryo 

 is formed from two similar cells, in which the differences are 

 entirely and permanently accommodated together, the further result 

 follows that the hybrids, like any other stable plant species, repro- 

 duce themselves truly in their offspring. The reproductive cells 

 which are formed in their seed vessels and anthers are of one kind, 

 and agree with the fundamental compound cell [fertilised ovum]. 



With regard to those hybrids whose progeny is variable we may 

 perhaps assume that between the differentiating elements of the 

 egg and pollen cells there also occurs a compromise, in so far that 

 the formation of a cell as foundation of the hybrid becomes possible; 

 but, nevertheless, the arrangement between the conflicting ele- 

 ments is only temporary and does not endure throughout the life of 

 the hybrid plant. Since, in the habit of the plant, no changes are 

 perceptible during the whole period of vegetation, we must further 

 assume that it is only possible for the differentiating elements to 

 liberate themselves from the enforced union when the fertilising 

 cells are developed. In the formation of these cells all existing 



could we otherwise explain that among the offspring of the hybrids both original 

 types reappear in equal numbers and with all their peculiarities ? If the influence 

 of the egg cell upon the pollen cell were only external, if it fulfilled the role of a nurse 

 only, then the result of each artificial fertilisation could be no other than that the 

 developed hybrid should exactly resemble the pollen parent, or at any rate do so 

 very closely. This the experiments so far have in no wise confirmed. An evident 

 proof of the complete union of the contents of both cells is afforded by the experi- 

 ence gained on all sides that it is immaterial, as regards the form of the hybrid, 

 which of the original species is the seed parent or which the pollen parent, 



