156 BEES AND BEE-KEEPING. 



of objective. The greatest peculiarity of this cell- 

 layer consists in the arrangement and abundance 

 of its small tracheae (Fig. 34), which do not pass 

 over the upper or lower surfaces of the cells, but 

 travel between their contiguous walls, in such vast 

 numbers, and with such repeated loopings, that con- 

 stantly as many as five or six interpose in a space 

 which cannot be greater than the 2 J- Q th of an 

 inch. The larger tracheae (tr), supplied from the ab- 

 dominal air sacs, divide into finer ones, which imme- 

 diately plunge between the cells, and there take a 

 course which, in the aggregate, amounts to about 60ft. 

 in length. This great need of oxygen for wax secretion 

 is highly suggestive, and will make clear a difficult point 

 when treating hereafter of the chemistry of the hive. 



Wax, like every secretion, vegetable or animal, is 

 at first liquid. It is derived from the blood by cell 

 action, and then, transuding the structureless membrane, 

 assumes the solid form of the scale, which, if lifted 

 when the gland is active, will always show that it is 

 fluid beneath. While examining this question, I was 

 struck by finding that the webbed hairs (wh, Fig. 32) 

 had their webbings in part or wholly covered by a 

 perfectly fitting casing of pure wax, which could only 

 have arisen by a transference of the secretion, while 

 still fluid, to their surfaces. 



Turning our attention now to the wax scales, we find 

 them to differ from the wax of comb. They are much 

 more brittle and transparent, being not unlike flakes 

 of talc. Turpentine dissolves them immediately with- 

 out residue, whilst fragments of comb disappear but 

 slowly in the same medium, which they make cloudy. 



