1904.] PACKARD— ORIGIX OF MARKINGS OF ORGANISMS. 437 



Several of my students whom I asked about the matter, after 

 showing them a stuffed specimen and explaining the theory of 

 blending, have related their experience. Mr. C. A. Weeks tells me 

 that he noticed a blending of the stripes while seeing a chipmunk 

 running. Mr. T. McA. Webb reported that the chipmunk when 

 running '* appears all one color." Mr. J. H. Breslin writes, ** I 

 have often gone shooting for chipmunks, and found it very difficult 

 to shoot one because it is so difficult to see it. I have often seen 

 them on the rails of fences, and when you look right down upon 

 one, it looks like part of the rail." 



Mr. T. E. B. Pope tells me that ^* when the chipmunk runs 

 slowly the black stripes are very distinct, but when running rapidly 

 the dark stripes along the back appear to blend, so that the back 

 appears dark as compared with the reddish or chestnut color of the 

 under side ; there is a black mass above and a chestnut mass 

 beneath.'' 



Mr. Glover M. Allen writes: " I have never looked particularly 

 for the blending of stripes in the chipmunk as it runs, but my 

 recollection would be that the stripes are not distinctly seen in 

 rapid movement, and the general effect is of a brownish animal." 

 He tells me that he has since observed that when it runs slowly the 

 white stripes are distinct, but the dark ones less so. 



Mr. W. J. Long writes me : The effect of the stripes is when it is 

 running to make a blur of the animal, making it a difficult object for 

 hawk or owl to hit. I used to try sighting a gun or rifle at chip- 

 munks (not to shoot, for I am especially fond of the little creatures) 

 and was surprised to find how hard it was to catch him with the 

 head, much harder than a running red squirrel for instance. The 

 stripes also help it when it is sitting still, for it gives at times the 

 curious effect of sunlight streaming down between the leaves or 

 twigs making bars of light and shade. The same results of the 

 stripes may be noticed in young woodcock, as mentioned, but not 

 carried out, in my " Little Brother to the Bear." 



I also inquired of Mr. Abbott H. Thayer whether he had 

 observed the blending of the stripes, and he kindly wrote me as 

 follows : 



** Chipmunks, like the vast majority of mammals and the whole 

 animal kingdom, with exceptions almost wholly confined to male 

 birds, are graded from dark above to white beneath in exactly the 

 degree to efface their appearance of normal rotundity, and hence 



PROG. AMER. PHILOS. SOC. XLIII. 178. CC. PRINTED JAN. 24, 1905. 



