240 PROF. «. MACLOSKIE, D.SC; LL.D., ON 



energies in the ultimate cell involving its apparent choice of 

 materials suited to its multiplication and the reproduction of charac- 

 ters peculiar to itself. 



Apposite to the law of economy of material i(. may be often seen 

 that not one, but many organs which have been necessary to an 

 animal during one stage of its existence are suppressed, or become 

 rudimentary in a subsequent stage. So, in preparation for the 

 exigencies of altered surroundings, perhaps many organs of the 

 same animals simultaneously develop themselves, the functions of 

 which were not required antecedently. 



As may be seen in some other insects, M. Kllnckel Hercules has 

 recently shown that germs of the wings, of the legs, of the mouth 

 parts, and the eyes are to be traced in the larvae of YolucellaB long- 

 before they can be beneficial to the two-winged imagoes which alone 

 possess these organs. 



This convergence of lines connected with the elaboration of 

 useful parts towards the fulfilment of a particular economy has 

 been considered under the theory of probabilities ; and the 

 evidence is overwhelming against the likelihood of such a converg- 

 ence being the result of a purposeless variation. 



The author of the above cited paper well remarks that the scien- 

 tific investigator may not feel it necessary to ask from whence energy 

 and matter proceed, or who gave them the qualities they have. Yet 

 he may have scientific objections to urge against the philosophic 

 speculation, that mind and matter are convertible and modifi- 

 cations one of the other; thereby excluding the possibility of 

 extra-physical existences. 



As one out of a thousand examples of the simultaneous correla- 

 tion of parts in insect life, the interesting economy of TjHstalis 

 tenax may be cited. The imago of this handsome Dipterous 

 fly is in habit a complete contrast to its larval condition. The 

 former is furnished with large compound eyes and stemmata. It 

 is vivid in its action whilst on the wing, either poising itself over 

 flow^ers, or swiftly darting from one sunbeam to another. The 

 abdomen is broad and flat, and only sufficient to contain the 

 small, and often almost rudimentary, viscei'a of the insect. This 

 form of abdomen we may well believe acts as an aerial rudder, by 

 which the remarkable dodges on the wing are executed, in avoid- 

 ance of the capturing net. The acuteness of this insect's 

 vision, and the consequent instantaneous response made by its 

 large wing-muscles on the approacb of danger may be noted. 



The keen vision of the male and his increased activity, may be 



