The AMERICAN BOTANIST. 115 



Weiss with its dense, white, W00II3' coat is so formed in 

 order that mists or cold may not penetrate or clog the 

 stomata nor the burning sun's rays do any harm during 

 daylight hours ; and in our own land there are interesting 

 and pretty examples of a similar kind of growth in the 

 case of the wild filago and various species of cud-weed, 

 dwellers in spots where the sun strikes fierceh' in the heat 

 of the day. Manj^ cliinbing plants, such as rmmer bean, 

 hop and wild cleavers, show curious hooked hairs ; these 

 act as grappling irons and greath^ assist the structure to 

 grow on foreign supports ; while a vast number of other 

 species, in order to w-ard off browsing animals, clothe 

 themselves with a felt or web or hair so dense that to 

 anything attempting to eat it the effect would be most 

 unpleasant and choking. The beautiful great mullein is a 

 good example of this. It has been proved, too, that hairy 

 plants are far less frequently attacked by aphis or plant 

 lice than those that are smooth textured. Browsing 

 animals for the great part, as w^ell as most insects (except 

 snails and a few caterpillars) are kept a bay hj means of 

 stinging hairs in the nettles, the burning acrid juice secret- 

 ed by the latter proving extremely disagreeable to any- 

 thing or anyone who carelessly bruises the plants. 



When hairs are found actuallj^ on, or within the flower 

 itself, the fact maV be recognized that they are invariably 

 formed there in order to exclude unbidden guests, as ants 

 — small creeping insects being of no use whatever in the 

 great work of cross fertilization, but rather, indeed, injur- 

 ious in so far as they rob the blossom of its pollen, but fail 

 to conve3' it safely to an^^ other. Frequently these hairj' 

 guards are very dense, forming such an impenetrable bar- 

 rier that certain (and these are the non-welcomed) insects 

 cannot enter, while the^^ offer no hindrance at all to others 

 whose long, thin proboscides can easily'' thrust themselves 

 between the hairs or deliberately push open the apparent- 

 ly closed doorway. 



If hairs be carefulh' examined they w^ill be found to be 

 outgrowths of the epidermal cells and may occur on 



