176 Natural History. [Chap. III. 



some enlightened inquiries into the structure of 

 plants; but they made little progress, compared 

 with what has since been done. Early in the cen- 

 tury under review, the rev. Dr. Hales, of Great 

 Britain, pursued this investigation with great acute- 

 ness and diligence, and in his Vegetable Statics 

 presented the world with a mass of information 

 which will be long read and admired. About the 

 same time, Duhamel, of France, was busily and 

 successfully engaged in similar inquiries, and in his 

 Physique des Arbres, and other publications, threw 

 much new light on this part of botanical science. 

 Duhamel was followed by Charles Bonnett, of Ge- 

 neva, who proved one of the most distmguished 

 vegetable physiologists of the age. His Traite des 

 Feuilles is particularly curious and valuable. 



Towards the close of the seventeenth century 

 some attention had been paid to the different kinds 

 of Hairsy which constitute a downy covering upon 

 the surfaces of vegetables. But it was not till the 

 year 1745, that this subject was treated in tlie 

 full and masterly manner it deserved. In that 

 year M. J, Stephen Guettard, a very ingenious and 

 learned French botanist, began to publish his ob- 

 servations on the hairs and glands of plants. 

 These observations he continued during several 

 succeeding years. He has even established a bo* 

 tanical Method, deduced from the form, the situa- 

 tion, and other circumstances, of the hairy and 

 other glandular appearances on the surface of 

 plants. He has shown, w^hat perhaps w^ould hardly 

 have been suspected, that these appearances are, 

 in general, constant and uniform in all the plant3 



