May, 1895. CORRESPONDENCE. 359 



Mr. Galton, strangely enough, appears to overlook the fact that this theory 

 of discontinuous variation between definite positions of organic stability, so far from 

 in any way running counter to the theory of selection, entirely harmonises there- 

 with : for the alleged process, if indeed a vera causa, must always be controlled by 

 the master-process of Natural Selection. Clearly, if the — organically stable — 

 characters produced by such discontinuous variation be disadvantageous to the 

 species and ill-adapted to its requirements, they will immediately be swept away by 

 Natural Selection. 



This I find — as might be expected — insisted upon by Mr. Wallace in the second 

 instalment of his article ; but he strangely ignores the consideration that if such 

 (alleged) variations prove advantageous, the work of Natural Selection is really far 

 shorter and easier than we had hitherto supposed possible. This may be shown by 

 a series of propositions, based on the assumption that Mr. Galton has found a vera 

 causa. (1) Such sports, being the expression of definite positions of organic 

 stability, will occur more frequently than mere "chance" variations. (2) They 

 are, therefore, less likely to be swamped by the interbreeding which Darwin 

 recognised as fatal to "chance" sports; and, especially when particulate, 

 they are likely to hold their own in at least a proportion of the offspring. (3) Even 

 were all such sports swept away by some disease or catastrophe, yet precisely the 

 same varieties would soon re-occur in another generation, since they are the result 

 of definite positions of organic stability. (4) Since such sports may, in one genera- 

 tion, achieve by a bound a position that could be attained only after many 

 generations by the cumulation of small varieties, then clearly the process of species- 

 making is greatly shortened. (5) It would appear, therefore, that a species may 

 appear more than once, i.e., may reappear even if once extinguished. (6) Obviously 

 all such sports — the result of discontinuous variation — will be, when advantageous, 

 preserved by selection even more certainly than will slight variations. 



On the other hand, however, a sudden sport may often prove prejudicial to the 

 species, although the same variation, reached by slow stages, would be beneficial ; 

 for the suddenly varying species may outstrip the slowly varying environment. 

 For instance, the protective efficacy of mimicry depends upon the mimicking insect 

 keeping pace with the mimicked ; and if the latter — here the "environment " — vary 

 slowly, so must the former : a sport of the mimickers, anticipating by centuries the 

 final coloration of the mimicked, would be fatal. But sports in insects mimicking 



leaves would probably be beneficial. 



F. H. Perry Coste. 

 Ravenshoe, Burnt Ash Hill, S.E. 



Minneapolis and the Central Zoological Bureau. 



Recent inquiries and suggestions from some of your immediate neighbours 

 impel me to send you these few lines bearing upon your editorial " A Universal 

 Zoological Record," in No. 34, vol. v., of yotir valued periodical. 



The editorial seemed rather unfair to Mr. Barrows, who is printing a card 

 catalogue of some zoological literature under my supervision, and for that reason I 

 desire to give you a few facts in regard to the card catalogue we offered. 



For several years we have been printing a card catalogue of the zoological 

 literature available to the students in the Department of Animal Biology of the 

 University of Minnesota. Last year we decided, at the suggestion of Dr. Thos. G. 

 Lee, of this University, to offer to others what we had, and in the event of receiving 

 sufficient encouragement make arrangements for obtaining the titles of all zoological 

 articles. 



At this time there was no evidence that Dr. Field's international bureau had 

 any vitality, and we felt the way was clear for Mr. Barrows to issue his circular 

 under date of August 10 without any apologies. To this circular we received 

 encouraging and highly complimentary letters from all parts of our own country 

 and from England. Some, without further questioning, sent in their subscriptions 

 on the rather indefinite and extreme terms of the circular letter. The circular also 

 brought us a kind letter of surprise from Dr. Field. To this we replied promptly, 



