208 MEXTAL EVOLUTION IN ANIMALS. 



a fretted mass," wliich they used as moss. Again, Andrew 

 Knight observed that his bees availed themselves of a kind 

 of cement made of wax and turpentine, with which he had 

 covered decorticated trees — using this material instead of 

 their own propolis, the manufacture of which they discon- 

 tinued ;* and more recently it has been observed that bees, 

 " instead of searching for pollen, will gladly avail themselves 

 of a very different substance, namely, oatmeal." t 



Again, Osmia aurulenta and 0. hicolor are species of bees 

 which construct tunnels in hard banks of earth or clay, in 

 which they afterwards deposit their eggs — one in each parti- 

 tioned cell. But when they find tunnels ready-made (as in 

 the straws of a thatched roof) they save themselves the 

 trouble of employing their instincts in the way of tunnel- 

 making — merely building transverse partitions in the tube to 

 form a series of separate cells. It is specially remarkable 

 that when they thus utilize the whorl of an empty snail-shell, 

 the number of cells which they partition off is regulated by 

 the size of the shell, or the length of the whorl. Moreover, 

 if the whorl proves too wide near the orifice of the shell for 

 its walls to constitute the boundaries of a single cell, the bee 

 will build a partition at right angles to the plane of the 

 others, so forming a double cell, or two cells side by side.J 



Now, in all these cases it is evident that if, from any 

 change of environment, such accidental conditions were to 

 occur ordinarily in a state of nature, the bees would be ready 



* PMl. Trans., loc. cit. 



f Origin of Species, p. 228. It is interesting in connection witli these 

 facts to note liow singularly well tliey happen to meet a criticism of Kirby 

 and Spence, wliicli was advanced before tbey bad been observed, with the 

 object of discrediting the view of instinct being modified by intelligence. 

 These authors ask {loc. cit., vol. ii, p. 497), why, if such were the case, should 

 not bees sometimes be found to use mud or mortar instead of precious wax or 

 propolis : '' Show us," they say, " but one instance of their having substituted 

 mud for propolis .... and there could be no doixbt of their having 

 been guided by reason." It is curious that this demand should so soon have 

 been met by so apposite an obsei-vation. Doubtless mud is not so good a 

 material for the purposes required as propolis, but as soon as the bees are 

 fm*nished with a substance that is as good, they are ready enough to prove 

 their '" reason," even to the satisfaction of what was supposed, a priori, a 

 crucial test. This case should serve as a warning against the use of the ques- 

 tion-begging argument, which where any degree of evidence is presented of 

 intelligence compounded with instinct, forthwith raises the standard and says 

 — ShoA\- us an animal doing this or that, wliich would be still more remark- 

 able, and then we shall be satisfied. 



X See F. Smith, Catol. Brit. Kymenoptera, pp. 159-60. 



