2 ON THE HAIRS OF PLANTS. 



and that all that was taken for perspiration by botanists was 



. ... one of two thiiios: either 1st, a sort of hair, or instrument in 



Source of the » . . . „ 



tkceptioa. that shape, for carrying water to the mtesMor of plants, and 



pevforming many of those important services, which their 

 diminutive appearance makes us overlook ; or, 2dly, a sort 

 of cryptogamian plant, wholly nourished by the dews of the 

 atmosphere, and proving what they are by passing, like all 

 other plants, from flower to fruit and seed, and showing in 

 each various alteration the concomitant properties of e.ich. 

 That both these appearances have been taken for perspir- 

 ation there can be no doubt, since I have repeatedly and 

 regularly followed them in every plant peculiarly said to 

 perspire much; and always found it either a fruit or an in- 

 strument: and instead of being bubbles of water issuing 

 from the cuticle (as is supposed) their make alone would 

 prove the contrary, as they could not transpire on stalks. 

 Even the vineball is proved to have a stem ; and is therefore 

 an instrument, not a bubble. Before I give a more am- 

 AnotheroVec- P^^ description of these, I shall adduce a farther objection 

 tion. to the idea of perspiration; and prove the impossibility of it 



by the disclosure of a discovery I long ago made, but would 

 not give to the public, till perfectly convinced of its reality. 

 I have already said, that there is found in the corolla of 

 flowers, and in the stem of trees, a clear transparent skin, 

 which, placed under the most excessive magnifier, shows, no 

 alteration of form, nor can any aptiture be discovered in it. 



_, ^ . The same is found on the exterior of the cuticle, on each 

 The exterior . ' 



skin "of leaves side of the leaf of all plants; so that it is not possible that a 

 IS without drop of water can pass to or from the interior in this way, 

 though certainly air may. It is difficult to clear the skia 

 from all the marks the pattern of the pabulum leaves on it, 

 which were taken by all botanists for the pores in the cuti- 

 cle. I was once of this opinion ; but I have since with such 

 excessive pains laboured to elucidate this subject, and to 

 prepare for the microscope upwards of forty specimens, 

 (cleared in the way described in a former letter;) which in 

 this state were thoroughly examined by myself and others; 

 thatthertt can be no doubt of their being on both sides im- 

 pervious to moisture. They are divided into small com- 

 ^ partnaent* by a narrow vessel; and so extremely fine is th« 

 '■-'-■■' skift 



