of' the Chimney Swallow. 233 



is to be remembered, that this supposition is not contrary to the 

 first rules of philosophising, even were it proved that the Hi- 

 rundo rustica does migrate : For it is not adducing more causes 

 than are necessary, but merely arguing in accordance with a 

 fact ; and, though the fact may not be considered as perfectly 

 conclusive, since this group were so unfortunately disturbed, 

 and their capacity of retaining life during the winter, therefore, 

 unascertained ; yet, to destroy the validity of the reasoning, it 

 is necessary to shew, that animals, which are torpid for a month 

 or six weeks, cannot continue so for a longer time, without the 

 total loss of their vital principles ; in other words, that the sus- 

 pension of organic action, in such animals, for a longer term 

 than six weeks, is equivalent to the total abolition of such ac- 

 tion. Those that become dormant amongst us are known to 

 have the period of torpidity determined by circumstances pure- 

 ly adventitious, such as an early or a late spring ; and, if it be 

 legitimate to reason analogically in the present instance, the 

 torpidity and resuscitation of the above-mentioned group of 

 swallows, six weeks after the disappearance of the rest of the 

 species, must be as conclusive, in every respect, as if they had 

 been found and roused to feeling after a dormancy of six 

 months. 



I would beg to add, in speaking of this interesting bird, that, 

 like the Tetrao tetrix, and several other birds, he frequents si- 

 tuations, for many seasons, which he deserts without any appar- 

 rent cause. Thus, Gleneveraw, Argyleshire, the residence of C. 

 Campbell, Esq. was a favourite resort of the swallow, and his evo- 

 lutions, as he hunted his favourite insects, were a constant 

 source of amusement to the intelligent proprietor of the place ; 

 but, in 1826, only a few pairs were seen, while the situation of 

 the rest seemed to be occupied, and their office performed, by 

 the common bat ( Vespertilio murinus)^ which, contrary to its 

 usual habits, ventured boldly forth, during the brightest hours 

 of that bright season, and, seemingly exulting in the more than 

 ordinary number of Phalaenae which fell to its share, glided 

 along under the shade afforded by the larger trees. As late as 

 26th May of this year, no swallow had been seen in this part of 

 Gleneveraw. 



The sand-martin (Hirundo riparia) might, I should sup- 



