272 CONCLUDING REMARKS CHAP. VI. 



as their parents, whilst in the third case they belonged 

 to all three forms. 



The cases hitherto given relate to illegitimate unions, 

 but Hildebrand, Fritz Miiller, and myself found that 

 a very large proportion, or all of the offspring, from a 

 legitimate union between any two forms of the tri- 

 morphic species of Oxalis belonged to the same two 

 forms. A similar rule therefore holds good with unions 

 which are fully fertile, as with those of an illegiti- 

 mate nature which are more or less sterile. When 

 some of the seedlings from a heterostyled plant belong 

 to a different form from that of its parents, Hildebrand 

 accounts for the fact by reversion. For instance, the 

 long-styled parent-plant, of Primula veris, from which 

 the 162 illegitimate seedlings in Table 36 were derived 

 in the course of five generations, was itself no doubt 

 derived from the union of a long-styled and a short- 

 styled parent; and the 6 short-styled seedlings may be 

 attributed to reversion to their short-styled progenitor. 

 But it is a surprising fact in this case, and in other 

 similar ones, that the number of the offspring which 

 thus reverted was not larger. The fact is rendered still 

 more strange in the particular instance of P. veris, for 

 there was no reversion until four or five generations of 

 long-styled plants had been raised. It may be seen in 

 both tables that the long-styled form transmits its form 

 much more faithfully than does the short-styled, when 

 both are fertilised with their own-form pollen ; and why 

 this should be so it is difficult to conjecture, unless it be 

 that the aboriginal parent-form of most heterostyled 

 species possessed a pistil which exceeded its own stamens 

 considerably in length.* I will only add that in a state 



* It may be suspected that this Scott, 'Journal Linn. Soc. Bot.,' 



was the case with Primula, judg- vol. viii., 1864, p. 85). HerrBreit- 



ing from the length of the pistil in enbach found many specimens of 



geveral allied genera (see Mr. J. Primula elatior growing in a state 



