262 ANIMAL SKETCHES. CHAP, 



recovery from which he was unable even to approach 

 them without exciting their anger. It is probable that 

 humble-bees seek their mates by the aid of smell. 



The correct localization of the organ of smell has been 

 a matter of difficulty. Kirby and Spence localized it at 

 the extremity of the " nose/' between it and the upper 

 lip. That the nose, they naively remark, corresponds 

 with the so- named part in mammalia, both from its 

 situation and often from its form, must be evident to 

 every one who looks at an insect. Lehmann, Cuvier, and 

 others, misled by the fact that the organ of smell is in 

 us localized at the entrance of the air-track, supposed that 

 at or near the spiracles of insects were the organs of 

 smell. These spiracles constitute the breathing apertures 

 of insects, for the bee and the beetle and the butterfly, 

 and the caterpillars or grubs from which they develop, do 

 not breathe by the mouth but by openings in the sides of 

 the body. In the worker-bee there are two such spiracles 

 on each side of the mid-region of the body or thorax, and 

 and five on each side of the abdomen. The queen-mother 

 has the same number ; but the drone has an extra pair 

 on the abdomen. The spiracles form the external open- 

 ings of a system of tubes and cavities called the tracheal 

 system, by means of which the respiration of insects is 

 effected. 



In all animals the life-giving oxygen must in some way 

 be brought to every cell and fibre of the organism. When 

 we breathe air into our lungs the oxygen it contains finds 

 its way into the myriads of little bags which form the 

 terminations of the branching air-tubes. Around these 

 bags the blood freely circulates. And in the blood there 

 are a number of red blood-discs, which are like minute 

 boats that can be laden with oxygen. Laden in this 

 way as they pass through the lungs, the blood-discs with 



