VARIATION STEPS • 187 



numbers of rays remained practically unchanged" (VERNON, 



loc. cU., p. 51).^ . . „ ^ .,, 



On the other hand, DE VRIES, " startmg m 1896 with 

 plants which had 21-ray florets occurring most frequently in 

 their capitula, and none of which had more than 23 florets, 

 picked out each year the two or three plants richest in florets 

 for breeding with, and sowed their seed the following year. In 

 1897 a single flower was obtained, having 34 florets, but the 

 2i-floret form was stiU the commonest. In 1898 one of the 

 flowers had 48 florets, the commonest flowers now having 26 

 or 34 florets. In 1899 one had 67 florets, the commonest form 

 having 26 or 33 to 35 florets, and in 1900 one had loi florets, 

 the commonest form having 47 florets." (VERNON, loc. cit., 



P- 63.) 



I think it would be premature to conclude from the above 

 very important experiments that two hereditary forms (sub- 

 species ?, pure hnes ?) were mixed in the original group of 97 

 specimens. It may be surmised that the results of selection 

 have been influenced by the existence of variation steps — i.e. by 

 a specific energy of the examined property. 



The differences between the 97 original specimens were 

 probably produced by two groups of factors : (i) differences in 

 the conditions of existence (of the specimens) which are un- 

 avoidable (plasticity) ; (2) differences in the quantitative com- 

 position of the living mixture (§ 8A).^ 



Selection being carried out, specimens of different quantita- 

 tive composition have been picked out and isolated, the differ- 

 ences being increased (within certain limits) by continued 

 selection. The progress (in respect of the observable property), 

 instead of being gradual (by impalpable changes) has been very 

 rapid, proceeding, as it were, by jumps, because of the existence 

 of variation steps. 



In other words, in this example each of the figures 13, 21, 34, 

 etc., considered in itself is not an hereditary property of the 

 species or of one or another subspecies (race, form, etc.), but 

 what is transmitted by inheritance is the specific energy, 

 expressed by a Fibonacci series of the second degree. 



§ 180.— VARIATION STEPS, DISCONTINUOUS VARIA- 

 TION AND SPECIFIC DIFFERENCE.— Two given species 

 (subspecies, etc.) are always strictly different by the qualita- 

 tive composition of their living mixture and therefore by their 



1 Taking ONLY the figures into account, it may be remarked that selection 

 has resulted here in a change of the curve similar to the changes produced in 

 Chr. carinatum by modified conditions of existence or by gradation (§ 128). 



^ The latter differences being themselves a consequence of differences in the 

 conditions of life of the parents, for the seeds were obtained from twenty 

 botanic gardens, thus from various countries. 



