hundred years, and even as late as the middle of the nineteenth 

 century, burdened with a mass of misinformation, such as, for 

 example, the notion that leaves are the lungs of plants, that they 

 inhale by one surface and exhale by the other, that in breathing 

 the inspiration was at night and the expiration at day. 



One preconception that was a hindrance to progress was the 

 idea that plants possessed a system of organs and functions 

 analogous to 'those of animals. This thought is most fully 

 elaborated in that strange poetical-scientific book, The Botanic 

 Garden, published in 1791 by Erasmus Darwin, grandfather of 

 the great evolutionist. " It is easy to conceive," says the author, 

 how a peristaltic contraction produces the flow of sap in plants. 

 "There is ... a complete circulation in the leaf; a pulmonary 

 vein receiving the blood from the extremities of each artery, on 

 the upper side of the leaf, and joining again in the foot-stalk of 



disperse the new blood over the new bark. . . . And I was 

 induced to believe the existence of a venous system correspond- 



es and pc 



:tals. 





I think th 





be 



no doubt 



es of tre< 



:s are 



their 



lungs. . . 



. The 



circi 



ulation in 



leaves of 



plant: 



s is ve 



:ry similar 



to that 



offish." 



1830 Br 



•ongn 



iart d 



escribed a 



circulat 



ion 



in plants 



that of the blood in 



animals. 









enough f 



or us 



to sr 



riile at the 



se crude 



:ide 



as, but I 



the scien 



tine w 



orld v 



vill be sayit 



lg ofus 



one 



hundred 



aw, or he 



)W bl" 



oadly 



the audien 



ce will ■ 





t then as 



r quotes 



from 



the 



books we 



take so 



sen 



iously, to 



dw superi 





the V 



mowledge 



of his t 



:ime 



over the 



of 1906. 



Th< 



ediffe 



rence betw 



een the 



Da: 



rwin who 



and the c 

 of menta 



1 abil 



how; 



fity, 1 



is born in 

 is of ment 



1809, is 

 al inhei 



not 



ce. The 



: have labored, we have reaped the benefits. 



r the work of Black, who discovered that car- 



mstituent of the atmosphere, of Ray and Boyle, 



