THE ORCHID REVIEW. 107 



freely enough in localities where the conditions are favourable. And we may 

 recall the interesting hybrid D. X Kingiano-speciosum from the collection 

 of Sir Trevor Lawrence, which was described at page 107 of our fourth 

 volume. 



MENDEL'S LAW OF INHERITANCE. 



Mendel's "Experiments in Plant Hybridisation" (see pp. 11, 45) though 

 not directly concerned with Orchids, assumed a special importance because 

 of an opinion expressed that his so-called " Law " would be found to be ot 

 general application. An important paper on the subject, by Dr. \V. F. R. 

 Weldon, has appeared under the title " Mendel's Laws of Alternative 

 Inheritance in Peas" (Biometrica, i, pp. 228-254, tt. 1-2), in which it is 

 shown that Mendel's results do not always agree with those obtained by 

 other observers, nor yet with the history of some well-known commercial 

 varieties of Pea. Even Mendel's " dominant" and " recessive " characters 

 work out differently for other varieties. The question is gone into in 

 detail, and there are two beautiful photographic plates showing the 

 variations of (1) colour and (2) form in six or seven welll-known varieties. 

 We cannot enter into details, as the subject does not come within our scope, 

 but the conclusions arrived at are important, in view of the opinion that 

 Mendel's Law would be found to be applicable to hybrids generally. 



Taking the net results of the various experiments and observations sum- 

 marized, Weldon concludes by saying— "I think we can only conclude that 

 segregation of seed-characters is not of universal occurrence among cross- 

 bred peas, and that, when it does occur, it may or may not follow Mendel's 

 Law. The law of segregation, like the law of dominance, appears therefore 

 to hold only for races of particular ancestry. The fundamental mistake 

 which vitiates all work based upon Mendel's method is the neglect o 

 ancestry, and the attempt to regard the whole effect upon offspring, produced 

 by a particular parent, as due to the existence in the parent of particular 

 structural characters, while the contradictory results obtained by those who 

 have observed the offspring of parents apparently identical in certain 

 characters show clearly enough that not only the parents themselves, but 

 their race, that is, their ancestry, must be taken into account before the 

 result of pairing them can be predicted." 



This objection should not apply to hybrid Orchids, obtained in the 

 first place from distinct wild species, and an examination of these in the 

 light of Mendel's law would be interesting. The difficulty of applying the 

 " Law " to those hybrids which reproduce themselves true from seed has 

 already been pointed out, and it seems possible that there may be another 

 explanation of the facts. 



