56 PROCEEDINGS OE THE COTTESWOLD CLUB 



generations, probably also assimilating metallic atoms. 

 Rejecting by evacuations the coarser substances, it retained 

 chiefly the juices of its food, and by a ])rocess which it were 

 in vain to try to understand even if in itself there was 

 outlined the future development of the animal, which in 

 the pupa l)ecomes more pronounced so that by a 

 momentary inspection in the case of many genera, we 

 can see without difliculty under the temporary tabernacle, 

 or hibernacle the eyes, the ])roboscis, the folded wings, and 

 so on, of the fly that is sooner or later to break its bonds 

 asunder. 



The voracious caterpillar when (-hanged into a moth 

 or l)Utterfly feeds on the daintiest of foods, and only very 

 sparingly on those. 



If we from feeding, turn to breathing, in these species 

 of animals, we note that the parts which have to do with 

 respiration arc the trachere and spiracles, together with their 

 associated muscles and nerves. The trachea; are the 

 ducts by which air is conveyefl from the exterior, and the 

 spiracles are the outer doors as it were. These are, 

 generally speaking, nine in number on each side, and 

 between the sj)iracle and trachea- there is a conical 

 " occlusor " muscle l)y which the tracheae may be closed 

 at will, and these conditions or others very similar exist 

 in the case of the larva. Nearly all the muscles and 

 nerves of each segment of the body are used in the act 

 of res])iration. It has not been, and here again 1 speak 

 only so far as 1 know, definitely ascertained how air is 

 renewed in the trachaea ducts ; it may be by contraction 

 of the dorsal vessels, or the opening or closing of the 

 muscle just referred to, or as some think, by the active 

 over-lapping of the segments of the body. In the grass- 

 hopper (Gryllus sp. viridissimus) about 37 contractions 

 per minute were observed when it was excited — several 

 short inspirations being followed by one long one. In 

 the hive bee there have been observed no to 160 



