CORRESPONDENCE. 



Experimental Evolution. 



In the last number or Natural Science, P. C. M. delivers some criticism o 

 my lectures on Experimental Evolution. He is quite right in criticising me when he 

 says that "While royal food may ripen the latent sex of a worker ()r bees) a dif- 

 ferent factor has to do with the distinction between male and female." I should 

 have said that sexuality, i.e., the development of sex, or the possession of sex, may be 

 determined by food ; stw is not determined thus, as while unfertilised eggs develop 

 only into drones, fertilised eggs, according to circumstances—and food— develop 

 into queens or workers. 



But when P. C M. says, concerning the statement that " we possess in the facts 

 of domestication and inheritance a large number of cases of variation, which occurs 

 in every part, due to environment, and transmitted in various degrees," that " if the 

 statement were true there would be no controversy," this is a rather sweeping 

 criticism. There are five distinct propositions in this statement. Does P. C. M. 

 object to all, cr only to part of them :-' Does he deny variation due to cultivation 

 and domestication ? does he deny the occurrence of variation in every part of 

 organisms? doss he deny only the fact that variation is due to environment? or does 

 he object to its hereditary transmission ? I grant that, in ascribing variation to 

 environment only, I would be saying more than I am prepared to assert, as, in fact, 

 the cause or causes of variation are unknown ; but environment in its broad sense 

 seems to have something to do with variation, as many facts go to show. P. C. M. 

 may certainly object to part of my statement, but it would be fair, if only towards 

 his readers, if he stated which part he considers as most heretical. 



The same critic informs me that Professor Le Conte's classification of the 

 factors of evolution is "curiously inept," and charges me with approval thereof, 

 which surely cannot improve my situation. However, I must decidedly object to a 

 method (?) of criticism (? ?) which consists in quoting part of a statement and 

 leaving out the remainder. I have merely given Le Conte's list of "what the 

 factors of evolution are, or are supposed to be " (p. 229 : there is not much approval 

 in this), and if P. C. M. had taken the trouble to go on with the quotation, and to 

 quote what I say of this list (which, in fact, is a mere enumeration of the principal 

 factors of evolution proposed on different sides, a mere catalogue), he would have 

 seen that I state that " the five factors are not all recognised by the same group of 

 evolutionists," the two first being especially I^amarckian, and that, in my opinion, no 

 definite view concerning the real value of these different factors can be entertained 

 as long as all have not been subjected to the test of experiment 



If I have "approved" of the list, I do not see that I can be considered as 

 having approved of the scientific soundness of the views expressed in it, inasmuch 

 as no one does adhere simultaneously to each of the five views expressed, and I 

 should be the last to do so, since I ask for proofs of each and all. 



P. C. M. ends with a very virtuous and mighty sentence, which, abridged, might 

 be of high moral use in a copy-book ; but I fail to see how it applies to myself. I 

 have not the slightest wish to confound anybody, nor am I familiar with the devices 

 of poHtical controversy— which, I perceive, are exceedingly wicked— and while 

 advocating, from the first to the last page, the necessity of submitting theories to 

 the test of experiment, in order to ascertain the exact situation of that swift- footed 

 fugitive, truth, I certainly did not expect to be charged with resorting to methods 

 which are not only unscientific, but. strictly speaking, unfair 



Paris, November, 1892. Henry de Varignv. 



