202 SOME SINGULAR THINGS 



the sesineiits are divided. The use of this cloth- 

 ing for the body is tolerably clear, since this pile 

 must prevent the too rapid evaporation of the heat 

 from the surface of the body ; for, although cater- 

 pillars would be classed among the cold-blooded 

 animals, they nevertheless have an internal heat 

 above that of the surrounding atmosphere, which 

 originates from the activities of the organs and 

 the respiratory function, and which they would 

 lose more rapidly but for this investing pile. 



But there are two other series of structures, always 

 arranged in longitudinal rows, the use of which 

 is wholly unknown. One of these is a universal 

 characteristic of all caterpillars in their earliest 

 stage, excepting probably the larger part of the 

 highest family, and is common to the later stages 

 of some of the lower families ; and that is the 

 special papilla-mounted bristles, which are fur- 

 nished with an expanded trumpet-mouthed tip and 

 are the ducts leading from glands at their base 

 secreting a transparent fluid, which, after secretion, 

 is borne in a little globule in the mouth of the 

 trumpet, and sometimes kept in its place by a few 

 microscopic bristles which surround its rim. That 

 these have some protective function is highly prob- 

 able, but what its nature may be, or how it acts, 



