ON THE SITPP09ED PERSPIRATION OP PLANTS. g^| 



III. 



On the supposed Perspiration of Plants* By Mrs. 

 Agnes Ibbetson. 



To Mr. NICHOLSON, 

 SIR, 



t\ FRIEND has suggested to me, that, to avoid all mis- Moisture mis- 

 takes, I should have described the various kinds of moisture, ta | ceri . for P^F- 



7 , ' spiration should 



that might be taken for the perspiration of plants; lest the be described. 



subject, from their appearance, should be given up as 



a dream of the author's, without a fair and candid trial. 



It is certainly worth it, for great must be its influence on Perspiration as- 



the atmosphere, and immense the calculation of the water znoxmoxxs 



necessary to afford such a perspiration, if we take into 



account also the quantity wanted for their growth. But, 



I may say, if leaves exude, in proportion to their surface, 



as much moisture as a healthy man, they must often drop 



water in the driest days; which I never could perceive they 



did. But if (as is insisted on) they yield 17 times as much 



as a robust subject, every tree must be a shower bath, and 



we could not sit under one without a complete wetting*. 



Of the various appearances of moisture, which the solar Different kinds 



microscope so completely elucidates, I shall first mention of apparent 

 r ; 7 moisture on 



the honey dew, though there are few not acquainted with plants. 



its appearance. Beside this, there are three others, one 

 the bladder iu which a small insect infolds its larva; another 

 sort in which au insect lays her eggs ; and the third is the 

 sickness of a plant ; for there are few plants, that do not 

 give out a sort of sugar when ill. After these I must men- 

 tion the egg of some insect. It is found on the proteas, 

 and one or two other plants. I have preserved the eggs 

 till the animals showed themselves. The next is the cryp- 

 togamia found on the pea, the sun flower leaf, the mimulus, 

 and a few others; of these I have given a sketch, just 

 as I took them from the solar microscope, that every one 

 may judge whether this looks like the perspiration of a 



* This does not follow,* unless some cause were present, to' con- 

 dense the aqueous vapour perspired. C. 



plant. 



