428 THE CANADIAN NATURALIST. [Dec. 



contents of the head of the honey bee, may be seen the singular 

 and somewhat puzzling connection between these air vessels 

 distended by their peculiar spiral fibres, and the salivary glands 

 of this insect. In this preparation it will be seen that, instead of 

 a large spiral vessel, dividing and sub-dividing into extremely 

 fine tubes, and these tubes ramifying over the part requiring 

 aeration (as in other cases), these tubes appear to be modified 

 and converted into the very gland structures themselves ? And 

 in another slide, may be traced the connection of these wonder- 

 ful air tubes, with the muscles, the ovaries, and the gizzard of a 

 flea. Perhaps I should remark by the way, that the existence of 

 this last mentioned organ, a flea's gizzard, was, some time since, 

 warmly discussed by a number of microscopists. It is well known 

 that insects, possessing a suctorial apparatus, are not usually 

 furnished with a gizzard, of which is essentially a grinding or 

 triturating organ. But the late Professor Quckett (whom it was 

 the writer's great privilege to know) asserted in spite of all 

 opposition, and contrary to analogy, that the flea possessed this 

 organ; and so it turns out! For the clever little Frenchman 

 who made this flea preparation for me, has managed to demon- 

 strate the fact ; and to mount the minute dissection (thus made 

 with an amazing amount of patient persevering skill) in a 

 most exquisitely beautiful manner. 



But what of these air tubes, about which so much has already 

 been said ? On examining the preparations which accompany 

 this paper, you will observe that they consist of two membranous 

 tubes— one inside the other — and that between these delicate 

 membranes, there is coiled a spiral fibre which tapers down 

 smaller and smaller, as the tubes subdivide ; and which continues 

 its course down to the most minute vessel that the microscope 

 can reveal. The purpose which this spiral fibre serves, affords a 

 striking and beautiful illustration of that marvellous design and 

 adaption, which is exemplified in the whole of the great Creator's 

 works. As these tubes contain only air, they would be liable to 

 collapse by the constant pressure of surrounding organs, and still 

 more by the violent contortions of the animal when moving about 

 were it not for these spiral fibres, which combine lightness, 

 firmness, elasticity, and every other needful requisite. So 

 admirably do they fulfil their intended purpose, that the human 

 inventor has copied them, to strengthen his elastic india rubber 

 gas pipes and other tubes of similar character. 



