January 20, 1893.] 



SCIENCE. 



?>7 



lived, however, some seven or eight weeks, were active, seemed 

 well and happy (?) and, as far as we know, never ate a mouthful 

 of anything during the entire time. I neglected to mention that 

 the old snake shed her skin once during her captivity, unfortu- 

 nately, it was during our absence, and we did not witness the 

 operation. 



It certainly seems strange tliat. with so much fasting, they 

 none of them should look thin and poor, but should apparently 

 grow and increase when having consunaed nothing. 



Mrs. W. a. Kellerman. 



Columbus, O., Jan. 9. 



Geographical Variation in Birds. 



In your issue of Jan 6 there appears a communication entitled 

 " Geographical Variation in Birds," containing several remarka- 

 ble statements, two of which I would like to correct. In speak- 

 ing of "desert coloration," this writer says: "If the scorching 

 sun of the desert renion.s will bleach out one species, why will it 

 not do the same for another 'i The plea of adaptation of coloration 

 for protection cannot be urged here." Such a conclusion does 

 not follow, and the plea of protective coloration might reasonably 

 be made, because the "bleaching" of which he speaks did not 

 take place during one summer, but is the result of natural selec- 

 tion for an unknown number of generations, and, while in some 

 species this protective coloration has proved beneficial, it does not 

 follow that in other species with different habits natural selection 

 would work along the same lines. 



But this is only a slight error compared to the following aston- 

 ishing paragraph, which I quote in full, the italics being my 

 own : — 



"Nut only are colors affected, but size as well, by geographical 

 position. This is probably more marked north and south than 

 east and west. And yet the variation in size alone is not sufficient 

 for a sub-specific division It is not at all strange that those indi- 

 viduals of a migratory species which push furthest north should 

 possess stronger bones and muscles and so be larger than those 

 which were not able to fly so far. It would seem natural that the 

 constant recurrence of such a difference would tend in time to 

 form a race peculiar enough to be recognized as a sub-species. 

 But it has not proven true thus far in the history of the world, 

 and why should there be any change under the same conditions?" 



If the above quotation means anything, it is that the author 

 believes increase in size to be more or less general and due to the 

 longer migrations of originally stronger individuals, and yet that 

 this process of selection has not up to this time produced even a 

 tenable sub-species ! Considering these two unique ideas in re- 

 verse order, let us see whether there are not some species, or at least 

 aub-species, based solely on an increase or decrease in size. Hastily 

 running over the list of North American birds, we find the follow- 

 ing interesting facts: Troglodytes alascensis is accepted as a dif- 

 ferent species from T. hiemalis, but the variation is only in the 

 size. Acoipiter velox differs from A. cooperi practically in size 

 only. Totanus melanolensus and T. flaripes are described by 

 Cones as "precisely the same" except for size. And, lastly, 

 Rallus vtrginianus is "a perfect miniature " of B. elegans, being 

 about forty per cent smaller. 



In addition to these species, we find there are at least sixteen 

 sub species which differ from the original stock only in size. 

 About half of these vary from east to west, the others north and 

 south. Furthermore, as Dr. Coues so truly says, many American 

 representatives of European species are "larger and better birds" 

 than their foreign relatives, but we will not include them here, 

 because there are generally some slight differencf s in coloration 

 as well. So much for the existence of sub-specific variation in 

 size; now. as to the idea that this increase is due to migration. 

 If it is so. how will we account for the cases already given in the 

 genera Accipiter and Totanus, where the differing species have 

 practically a co-extensive range; or for the even more difficult 

 case of Ballus, in which the smaller species is a much more 

 northern bird ? But the best illustration to show the fallacy in 

 both ideas is Dryobates villosus. Here we have a widely distributed 

 bird, a resident, not a migratory species, which has two accepted 



sub-specifS based solely on variation in size: the northern form, 

 D. V. leiicomelas. larger than normal, and the southern form. D. v. 

 audubonii, smaller. How can this be accounted for on the pro- 

 posed •• migration" theory? To sum up the whole matter, it is 

 probable that northern birds will average larger as a rule, especially 

 in resident species, as they are thus better fitted to stand the 

 severity of the climate and the other difficulties of boreal existence. 

 Furthermore, it can hardly be denied that variation in size is in a 

 number of cases not only sufficient to denote a sub-species, but, 

 occasionally, where the connectmg links have disappeared, to 

 form what is universally considered a distinct species. 



Hubert Lyman Clark. 

 Plttsburgli, Fa., Jan. 13. 



Pseudoaurora Not Shadows. 



The explanation of the phenomena reported by me in Science, 

 issue of the 16th of December, is altogether too common an ob- 

 servation to leave any doubt of its failure to clear up the mystery. 

 My calling has made me very familiar with all of the " shadows 

 cast upon the fog by projecting arms or objects in the beam from 

 the light," as "seen at any time when there is smoke, light fog, 

 or mist." 



The phenomena which I described was entirely new to me, and 

 apparently distinct from shadows of any kind, consisting of pen- 

 cils of li^ht radiating upward from a dark arc, the centre of which 

 was somewhat east of north, the pencils constantly changing in 

 length, and having an apparent movement laterally precisely like 

 those of the ordinary northern lights while I remained standing 

 still. The characteristic coloration of the pencils was unmistaka- 

 ble, hut not as distinct as I have sometimes seen it. I have seen 

 the "shadows" so often under similar circumstances of smoke, 

 fog, and mist, that I should scarcely have noticed the matter but 

 for the dark arc with its superimposed luminous arch and the 

 radiations described. But I spent considerable time in making 

 the different observations mentioned before, and took in the 

 familiar shadows that impress the mind of Professor Hazen so 

 strongly. P. L. Hatch. 



Anacorles, WatLlngton. 



Natural Selection at Fault. 



We are generally told by orthodox Darwinians that both the 

 structuf-e and the actions of animals are to a great extent depen- 

 dent upon natural selection. Any organ, or any habit which is 

 not advantageous to its species will be, it is said, promptly sup- 

 pressed as a possible danger, or at least, an unremunerative de- 

 mand. 



Yet there are a few cases of habits which seem to have been ac- 

 quired or maintained in flat contradiction to this doctrine. 

 Every one knows that the Felidce, from the Bengal tiger down to 

 our domestic mouser, when they have seized a prey do not at 

 once kill and devour it, but either torment it or at least sit and 

 watch it for some time before administering the fatal bite or blow. 

 The consequence is that the victim sometimes escapes, as we all 

 have witnessed, when pussy is playing with a mouse. One in- 

 stance at least is on record where a man, struck down by a 

 tiger, quietly drew a dagger and stabbed the assailant to the heart. 

 This could not have been done with a beast of prey of the 

 canine or ursine family, as they do not allow time for devising 

 and executing such a manoeuvre. Hence we see that the pecu- 

 liar conduct of the cats is disadvantageous to themselves, and we 

 ask why it has not been abandoned. Certainly any cat which 

 should at once devour any mouse or bird which it had caught 

 would, in times of scarcity, have a decided advantage over its 

 fellow- cats. 



Similarly injudicious is the conduct of the domestic hen. As 

 soon as she has laid an egg she at once announces the fact to 

 all whom it may concern by her well-known cackling. What 

 benefit is this outcry to herself or to her species? On the contrary, 

 the outcry is heard by animals which are given to stealing eggs i 

 and is understood by monkeys, if we may accept the evidence of 

 La Vaillant. There again, therefore, we have a line of conduct quite 

 contrary to what natural selection would determine. 



