698 JOUENAL OF THE EOYAL HOKTICULTUEAL SOCIETY. 



of every plant contains within itself immeasurable possibilities of rever- ' 

 sion to all or any of its ancestral characters, however remote, it is 

 clear that the apparent fixity of any species is a something bounded j 

 by time and conditions. For the time variation is bounded by the I 

 association of certain characters, but how or when this association will } 

 be broken, or what variation or reversion may then ensue, cannot be 

 foretold. ] 



This question of variation depends entirely on parentage, and could 

 probably be determined with some exactitude if the ancestry of any 

 plant was known. But inasmuch as the complete ancestry of no plant ! 

 can ever be known, and is in fact an impossible thought, all we can do is 

 to imagine that the earliest -known ancestors of plants with which we 

 deal possessed characters absolutely fixed and invariable, and from 

 this false basis to deduce certain mathematical ratios of probable 

 variation. On this assumption we may declare that a proportion will i 

 revert to one parental type, a proportion to another, and that such j 

 reverted individuals will have re-attained the same measure of fixity 

 that their parental types possessed. This has been known for a very 

 long time in a general way, and all the Mendelian advocates claim is 

 that in certain already tested cases they now know in what ratio such 

 reversions will occur ; but they do not claim that this ratio is applicable ! 

 in any general sense. My own experiments teach me that we can 

 only reach an approximation, not any precisely known result; and that 

 in different hybrids and cross-bred plants ihese results also vary, and- 

 are in great part dependent on the association of characters, and these- 

 again on pre-existing associations in their ancestors. 



Instances of Linked Ohakacteks. 

 [From my own observations.] 



(1) Chrysanthemum. — In C. indicum the flowers are small and 

 yellow ; the leaves small and permanently * glaucous on both sides ; 

 and the coloured bracts are markedly tri-dentate. G. indicum is held 

 to be one of the progenitors of our garden chrysanthemums. I have 

 raised seedling chrysanthemums from several sources, and have noted 

 that the bulk of gar(^en seedlings revert towards this wild type and 

 are inferior to the average of garden forms propagated by cuttings. 

 Amongst these partly-reverted forms some will always be found to have 

 reverted in a very marked degree, and these latter plants will show a 

 very large predominance of yellow-flowered forms. If these small 

 yellow-flowered forms are examined it will be found that they have 

 reverted to the specific type not merely in the respect of colour and 

 size of flower, but also in the permanently glaucous foliage and in 

 the tri-lobate margins of the coloured involucral bracts : thus showing 

 that the tendency is for these three characters to remain associated in 

 mongrel progeny. Of course if these seedlin^^ were true reversions to 

 the specific type — that had reverted in toto — this instance would in 

 some senses fail to help my argument, but the cases I have observed 



* That is, are glaucous in the young as well as in the mature stage. 



