ON THE HAIRS OF PLANT§. g 



skin, that, when placed in the sliders of my solar microscope, 



it is only on turning the light in a particular direction while 



the eye is on it, that it can be discovered. But the double 



microscope makes it very visible, let it be ever so nicely 



cleaned and prepared. I am hardly acquainted with any This skin seen 



part of the vegetable structure, that plays so many parts, '" «^*='y P*'^ 



and shows itself in so many ways, as this delicate skin. It ble struciHfe. 



was through this transparent skin 1 saw the dew drop enter 



the pal)ulnm. It is probably the same skin of which the 



hairs are formed, which confine not only water but air. 



How then can water enter the interior of the leaf, which Water enters 

 is thus guarded on both sides by this transparent medium ? \^ ^^,' , ; 

 that water which is often seen underneath the skin of vege- hkcTesseis. 

 tables, and wholly independent of the vessels? it is tp the 

 hairs alone they are indebted for it; which, however simple 

 they may appear to the casual observer, are very far from be- 

 ing so in reality. To these indeed plants owe many of the 

 most delicate and important offices, nor can a person see 

 them once, and have a doubt remaining as to their being real 

 instruments formed to effect some curious purpose. To give 

 a faint idea of this astonishing subject is all I can attempt, 

 for to collect .a tenth part of the various instruments these 

 hairs are intended to represent would be an endless labour; 

 and to account for the use and manner of acting of a few is I 

 fear more than 1 can perform well, or as I could wish. 



The first idea that occurs on seeing these hairs greatly They resemble 

 magnified is, that tliey resemble the instrumefits in an im- nientrof"a la- 

 mense laboratory. But great indeed must be the laboratory boratory. 

 that could show instruments of such contrivance, figures so 

 various, and mechanism so astonishing, even putting their 

 size out of the question. By the most careful attention to 

 their forms, by filling them with coloured liquids, and with 

 art and constant practice learning to manage the heat and. 

 light of my solar microscope (opaque as well as common), I 

 have been able repeatedly to fill and empty a few of the in- 

 struments, and by these means understand something of 

 th«ir construction. But it is extremely difficult to get a liquid 

 thin enough, as the most trifling degr^ of thickness chokes 

 the valves. This was the case with extremely diluted inks 

 still it itf to thia I owe the convicttJQBf. of the opening of the 

 B 2 ralvet 



