136 THE ORCHID REVIEW. {Sepr.-Oct., 1919. 
blue cotyledons showing through the semi-transparent seed-coats. Knight’s 
experiments began in 1787, and were recorded in a paper published in 1799, 
entitled ‘‘ Experiments on the fecundation of Vegetables” (Phil. Trans. R. 
_ Soc. Lond., xviii. pp. 504-509). These experiments were purely economic, 
and originated a number of new varieties, besides giving a number of 
surprising results, which were confirmed by Gartner, and amplified by 
Mendel. : 
Now that the discovery of Mendel’s long-overlooked paper has magnified 
these phenomena into a so-called ‘‘ Law of Heredity,” of all-embracing 
importance, it is well to view the facts in their true perspective. Experi- 
ments with Orchids, as with many other groups of plants, have given 
different results, except as to incompatibility and segregation, which are 
common features of hybridisation. Mendel’s results may have an element 
of utility to the breeder, as indicating facts that he may have overlooked, 
but it gives him no additional control over the factors with which he 
works. He has to deal with organisms as he finds them, not with selected 
characters, and when working for some particular quality, Mendelism 
cannot help him to exclude undesirable qualities which may also be present. 
As a theory of Evolution it can teach us little, being necessarily limited to 
the diverse characters that are united in hybridisation. With this limitation, 
Mendelian analysis may help us in tracing the distribution of such 
characters, or their recombination, but it can tell us nothing about their 
antiquity, or about the forces that produced them. The remark of a keen 
student of Evolution when viewing the results of a series of Mendelian 
experiments may be paraphrased so as to make it apply to Orchids. ‘It was 
something like this: ‘ It appears that we may get black or white, blue, silver, 
gray, fawn, or even chocolate, but it’s always an Orchid. Why is that ? 
A concise answer would indicate the limitations of this much overworked 
theory. _, 
Perhaps the limit was reached when Dr. Lotzy remarked: ‘‘ Now that 
Mendelism has been at work for well- nigh fourteen years, it seems to me 
that the time has come to apply it to Darwinian Evolution ... as 4 
logical consequence.” Examining the reputed causes of Evolution, and 
rejecting that of the transmission of acquired characters as inadéquate, he 
expressed his conviction that, “ with the possible exception of mutation by 
the loss of a factor, species are stable,” and he asked: “How do species 
arise? The answer is, I think, by crossing,” and he then proceeded to 
apply the theory to the occurrence of species in nature. Such an extension 
does not square with the existing distribution of species, but our remarks om 
this phase of the question must be deferred. 
