32 HISTORY OF BOTANY 



" the pithy part " is composed of " parench3Tiia " — a 

 term first introduced by Grew — and this is covered by a 

 " cuticle." The parenchyma encloses an " inner body," 

 the " hgnous part," obviously the vascular system or at 

 least the xylem part of it. He then describes, on the 

 whole correctly, the chief stages in germination, but the 

 underlying physiology is hopelessly wrong, because he had 

 no conception of the existence and activities of proto- 

 plasm. " The general cause of the growth of a bean, or 

 other seed, is fermentation. That is, the bean lying in the 

 mould, and a moderate access of some moisture . . . being 

 made, a gentle fermentation thence ariseth. By which, 

 the bean swelling, and the sap still encreasing, the work 

 thus proceeds." All through the writings of the early 

 physiological anatomists, and indeed in those of their 

 successors down to the beginning of the nineteenth century, 

 you will find this idea of sap fermentation taking the 

 place of what we nowadays regard as the functional 

 activity of hving protoplasm. 



Grew next proceeds to examine the root and finds it to 

 be composed of a skin, which he derives from the cuticle 

 of the seed, and a cortical body " commonly called the 

 barque " derived from the seed parenchyma. This 

 cortical body is porous, the pores, i.e. the cells, being 

 " innumerable " and " extream small." The central 

 ** Hgnous body " or vascular core, sometimes with and 

 sometimes without a pith proper, is on the whole correctly 

 described ; and he shows also how the cortical body 

 pierces " the hgnous quite through as far as the pith." 

 Obviously these " inserted pieces," as he calls them, are 

 what we know as medullary rays. 



How different was the physiological outlook in the 

 days of Grew to that with which you are so famihar you 

 may best realise from Grew's account of the functions of 

 the different parts of the root, and which I may summarise 

 in the following words : The root swells in the soil ; 

 some of the external fluids penetrate the cortex ; this 



