252 



NATURE 



[January io, iqoi 



tint appeared, which were from the first limited in their develop- 

 ment to the male sex, there would not be the least difficulty in 

 making a breed with the two sexes of a different colour, as, 

 indeed, has been effected with a Belgian breed, in which the 

 males alone are streaked with black." 



The necessary assumption of the theory of sexual selection 

 therefore is, not that spontaneous variations are always inherited 

 unisexually, but that congenital variations occur and have 

 occurred in certain species which from the first were limited in 

 development to one sex. The selection or preservation of such 

 variations does not explain their unisexual or other limitations. 

 It might be suggested or maintained that spontaneous hereditary 

 variations, limited to one sex, to one period of life, or to one 

 season of the year, are liable to occur and have occurred in all 

 species, but have been only selected and preserved in some. 

 But I do not know that this is maintained by selectionists, and 

 at any rate I know of no evidence to support such a contention. 



The questions I have considered are, Why have such heredi- 

 tary variations occurred in some species and not in others? Why 

 are they so closely correlated with the functional activity of the 

 testes, actually failing to develop normally in castrated animals ? 

 Why do they always, so far as we know, correspond to the special 

 stimulations involved in the behaviour of the animals under 

 sexual excitement ? 



Prof Meldola asks, Why should my view be supposed to 

 account for the limitation of the male characters to the male 

 and the Darwinian view to fail ? Surely it is obvious that 

 Darwin's theory merely assumes that variations have occurred 

 which from the first were limited in development as the 

 characters are, while my theory is that they were so limited in 

 development because they were due to stimulations similarly 

 limited. 



When Prof. Meldola suggests that the female has had any 

 tendency to inherit the male characters eliminated by natural 

 selection, he seems to me to be repeating an empty formula. 

 There is no ground for supposing that any selection could 

 eliminate such a tendency, and, further, it is an established fact 

 that the tendency has not been eliminated ; the female inherits 

 the characters potentially, but in her they usually remain sup- 

 prei'sed and latent to appear in actual development under certain 

 conditions. J- T. Cunningham. 



Penzance, December 29, 1900. 



Mr. Cunningham's reply does not appear to me to shed any 

 new light upon the subject of unisexual inheritance, and I can 

 only adhere to the statement expressed in my review. Why he 

 credits me with the supposition ' ' that all spontaneous variations 

 are inherited only by offspring of the same sex as the parents 

 in which they occurred " is beyond my comprehension. There 

 is nothing in my criticism of his views which warrants this, and 

 I need hardly add that the facts which prove such a supposition 

 to be erroneous are quite as familiar to me as they are to Mr. 

 Cunningham. The real point at issue is a comparatively simple 

 one. The author of the book insists that the theory of sexual 

 selection fails to account for unisexual inheritance, and that his 

 theory does account for this phenomenon. Again, it may be 

 asked, why ? The answer given above is simply a repetition of 

 his opinion, as already published— the characters are so limited 

 " because they were due to stimulations similarly lijjiited." That 

 is to say, that in every case where the male possesses distinctive 

 secondary sexual characters, these have been produced by direct 

 stimulations acting on the male only, and are, therefore, limited 

 by heredity to the male. Now Mr. Cunningham has just pointed 

 out that transference of male characters to the female does take 

 place, that blending of characters may, and does, occur, and 

 that male characters may, under certain circumstances, appear in 

 the female — a series of facts which we have all been familiar 

 with ever since we became students of Darwin's writings. These 

 facts are absolutely inexplicable on the " direct stimulation" 

 theory. If the stimulations which produced a male character 

 necessitate the restriction of that character to the male, then 

 the only way of escaping from the dilemma in which the author 

 has placed himself is to make one of two additional assump- 

 tions : — (i) The characters so blending are not secondary sexual 

 characters, which would be simply resolving the question at 

 issue into a verbal juggle ; or (2) that in all cases where there is 

 blending or transference, the same "stimulations" have acted 

 upon both sexes. This last assumption is, however, opposed to 

 the entire spirit of Mr. Cunningham's book, the whole burden of 



NO. 1628, VOL. 63] 



which is that there has been dissitnilartty of "stimulation" 

 between the sexes. 



I should like to add, in concluding, that my own opinion as to 

 the value of Mr. Cunningham's book is in no way shaken through 

 my inability to accept his amended Lamarckism. Out of 

 gratitude for the body of facts which he has collected, I will' 

 even go so far as to meet that much-hackneyed reproach of 

 " repeating an empty formula " which anti-selectionists are so 

 fond of using. For, after all, an empty formula, being (by defini- 

 tion) a formula containing no terms, is a negative kind of 

 expression, and if it cannot, by virtue of its vacuity, do much to 

 advance science, it cannot, on the other hand, do any harm. 

 But a formula which contains erroneous terms may throw us off 

 the track altogether, and my contention is that erroneous terms 

 exist in Mr. Cunningham's formula. R. Meldola. 



Direction of Spirals in Horns. 



In investigating the causes of directions of various spirals, I 

 discovered a certain law and order in the arrangement of the 

 direction of the spiral in horns which will interest many of your 

 readers. 



(i) That in the antelopes the right-hand spiral is on the left 

 of the head, and the left-hand spiral on the right of the head" 

 (crossed). (2) That in sheep the right-hand spiral is on the 

 right of the head, and the left spiral on the left side of the head' 

 (homonymous, or same name). The wild goats agree with the 

 antelopes in regard to the spiral direction of their horns (crossed), 

 and the oxen agree with the sheep in cases where the spiral can- 

 be noted (homonymous). Exceptions are not numerous and 

 not difficult to remember, but this letter is not intended to do 

 more than record the usual rules for spiral directions in horns. 



If these observations be of value in clearness of description of 

 a difficult point, it will be a gain ; and they may also prove use- 

 ful in classification. By taking a corkscrew (or a right-handed 

 spiral) in the hand, it is easy to verify on the horns themselves 

 the direction of their spiral curves. George Wherry. 



Cambridge. 



Liquid Air, 



The notion that Virgil had an idea of " liquid air" because 

 he speaks of " liquidus aer," is like the idea that Euripides was 

 a smoker because a line of his may have begun 



t\) ^ukx^k^" Sajprifia S6s. 



But there is a very curious anticipation of Prof. Dewar's dis- 

 covery in Lucian's "Vera Historia" Book ii 89. Lucian 

 there tells us that the inhabitants of the moon drink uTjp airoOXi- 

 fiofievos es Kv\iKa, " air squeezed or compressed into a goblet." 

 I do not know whether liquid air has yet been used as a 

 beverage, but in other respects the passage seems to be an 

 exact description of the substance in question. J. Adam. 



Emmanuel College, Cambridge, December 30, 1900. 



A Nest of Young Starlings in Winter. 



While a friend was walking through his fields near Brox- 

 bourne on Sunday afternoon, the 6th inst., he noticed a starling 

 flying towards an an old elm with some food in its bill, and orv 

 going up to the tree he found a nest containing young birds. 

 No doubt they are dead by this time, on account of the severe 

 cold and the difficulty the old birds found in obtaining food for 

 them. R. H. F. 



January 8. 



SOME ANIMALS EXTERMINATED DURING 

 THE NINETEENTH CENTURY. 



WHILE the century which has just closed may fairly 

 lay claim to the gratitude of posterity on account 

 of the magnificent tale of zoological work accomplished 

 during its course, it is, on the other hand, undoubtedly 

 open to the charge of having permitted the total exter- 

 mination of not a few animals, and of having allowed the 

 numbers of others to be so reduced that their disappear- 

 ance, at least as truly wild creatures, can scarcely be 

 delayed very many years longer. Possibly, if not prob- 



