2920 ] Correspondence. o41 



capacity" are alike of an order difficult for man to appreciate. But so 

 far as known the difference is one rather of degree than of kind. Applied 

 to the case of the wasp, Pelecinus, is not the established olfactory sense 

 sufficient to explain how the elusive males can find the females, thus being 

 drawn forth from their retirement, probably from no such great distances 

 as we may sometimes be led to imagine, and revealing themselves to the 

 comparatively dull visual faculties of the naturalist? Every hunter has 

 experienced a parallel case, hardly less striking, in the magical appearance 

 of swarms of blowflies which arrive to "inspect" his game almost as soon 

 as it is dead. It cannot be seriously questioned, I believe, that the highly 

 refined olfactory sense is adequate to account for all this, and that it is 

 the same in kind as that which brings the bear to the bait from afar and 

 enables the dog to trail his master through the crowded street. 



It is not the intention to deny the possible existence in animal life of 

 other senses than the orthodox five that come within the pale of human 

 experience; far from it. That the "homing sense" is a sixth one may well 

 be true. When we shall have learned more about the functions of all 

 parts of the internal ear and shall have added something more definite 

 to our knowledge of what has been called "muscle sense," then this ques- 

 tion may possibly be answered with a degree of assurance. While freely 

 admitting the attractiveness and stimulating effect of formulating working 

 hypotheses and theories, the point I wish to emphasize is simply that 

 we should first of all exhaust the explanatory possibilities of the scien- 

 tifically proven sense functions, in the analysis of observed phenomena 

 where matters of this nature are involved, before proceeding to draw 

 from the realm of the unknown. On the evidence adduced I feel that 

 this procedure has not been followed in the case of the two vultures, and 

 that the assumption of the existence of an "active sense which may be 

 called 'occult'" even "simply because it is hidden from the experience 

 and understanding of man," is not justified. 



Charles Eugene Johnson. 



Department of Zoology, University of Kansas. 



The Search for Food by Birds. 



Editor of 'The Auk': 



The following remarks suggest interpretations that may be placed 

 upon observations, different from those associated with them by Messrs. 

 Beck and Grinnell in 'The Auk' for January, 1920 (pp. 55-59 and pp. 

 84-88). In the former article, an occult sense is invoked to account for 

 Turkey Vultures finding the carcass of a mad dog thrown out of sight 

 in a sinkhole by fox hunters. From evidence given in the article, there 

 can be no certainty that the entire performance of killing the dog and 

 throwing it in the hole was not watched by buzzards. Had some of the 



