198 THE VEGETABLE WORLD. 
gravest defect of the system is, that by it the vegetable world is 
divided into two classes, namely, Herbaceous Plants and Trees—a 
division which has no existence in nature. The division destroys 
the natural analogies, for the size of a plant has no bearing upon 
its organisation and structure. In conclusion, the continually 
increasing number of new species which were unknown in 
Tournefort’s time, test, in the strongest manner, the defects of his 
system of distribution. The greater number of vegetable species 
discovered since Tournefort’s time could not be placed in either of 
his classes. This defect soon became very apparent, and the 
system fell by degrees out of favour with’ botanists even among 
his own countrymen, with whom it had found most favour. 
In England the study of plants had taken a more philosophical 
direction. About the middle of the seventeenth century the micro- 
scope was first applied to the study of the organs of plants, and the 
spiral vessel was detected by Henshaw, and shortly afterwards the 
cellular tissues were examined by Hooke. These discoveries were 
followed by the publication of two works on the Physiology of Plants 
by Malpighiand Grew. They examined the various forms of cellular 
tissues and intercellular passages in their minutest details, and with 
an exactness which causes their works still to be recognised as the 
groundwork of all physiological botany. The real nature of the 
sexual organs in plants was demonstrated by Grew ; the important 
difference between seeds with one and those with two cotyledons 
was first pointed out by him. Clear and distinct ideas of the causes 
of vegetable phenomena were gradually developed, and a solid 
foundation laid on which the best theories of vegetation have been 
formed by subsequent botanists. : 
About the time when Tournefort was engaged in arranging is 
system of plants, and when Grew had completed his microscopical 
observations, John Ray appeared, driven from his collegiate employ- 
ments at Oxford by differences of opinion with the ruling power® 
He sought and found consolation in the study of natural history, to 
which he was naturally attached, and for which his natural powers 
of observation, capacious mind, and extensive learning, so high!y 
qualified him. Profiting by the discoveries of Grew and other 
vegetable anatomists, in 1686 he published the first volume of his 
“ Historia Plantarum,” in which are embodied all the facts co? 
