NEHEMIAH GREW'S "ANATOMY OF PLANTS" 153 



concave of a Fiber." The phloem (bast) he naturally did not 

 detect as easily as the wood. He generally records "Sap 

 Vessels," as he calls them, occurring both outside the wood and 

 at the edge of the pith. The medullary rays he calls " Insertions 

 of Parenchyma." " These Insertions are likewise very conspicu- 

 ous in Sawing of Trees length-ways into Boards, and those 

 plain'd, and wrought into Leaves for Tables, Wainscot, Trenchers, 

 and the like. In all which, . . . there are many parts which 

 have a greater smoothness than the rest ; and are so many 

 inserted Pieces of the Cortical Body ; which being by those of 

 the Lignous, frequently intercepted, seem to be discontinuous, 

 although in the Trunk they are really extended, in continued 

 Plates, throughout its Breadth." Nehemiah Grew had more than 

 an inkling of the nature of secondary thickening. He tells us 

 that " every year, the Barque of a Tree is divided into Two Parts, 

 and distributed two contrary ways. . . . The outer Part falleth 

 off towards the skin ; and at length becomes the Skin in 

 itself. . . . The inmost portion of the Barque, is annually dis- 

 tributed and added to the Wood', the Parenchymatous Part 

 thereof making a new addition to the Insertions within the Wood; 

 and the LympJiceducts a new addition to the Lignous pieces betwixt 

 which the Insertions stand. So that a Ring of Lymphceducts 

 in the Barque this year, will be a Ring of Wood the next ; and so 

 another Ring of Lymphceducts and of Wood, successively, from 

 year to year." He goes on to show how different is the annual 

 growth in the case of different trees, and even of different years 

 of the same tree. He understood also the distinction between 

 Spring and Autumn wood ; " on the inner Verge of every annual 

 Ring of Wood, . . . the old sap-Vessels grow much more 

 compact and close together." Grew tells us then the common 

 opinion in his day was that " the Barque only surrounds the Body, 

 as a Scabbard does a Sword"', and points out that this is a 

 mistake, for they are truly continuous. " Now the reason why 

 the Barque nevertheless slips so easily from the Wood, is plain, 

 viz. Because most of the Young Vessels and Parenchymatous 

 Parts, are there every year successively formed ; that is betwixt 

 the Wood and Barque; where the said Parts newly formed, are 

 as tender, as the tenderest Vessels in Animals." 



Grew had only an imperfect conception of the cellular structure 

 of plants. The cells were not in his eyes the fundamental things ; 

 it was rather the fibres forming the cell walls which seemed to 



