The President's Address. By Wm. Carruthers. 133 



calls the fibres of the "lignous body." The only figures in this 

 little book for which the Microscope was used are the transverse 

 sections of Burdock (fig. 15) and Oak (fig. 17). 



The work opened up an untrodden field of investigation in 

 botany. Grew had nothing to guide him in his interpretations of 

 the structures he observed, He started with the conviction that he 

 would be helped by analogies in the structure and organisation of 

 animals. This became a constant source of error in his arguments 

 and generalisations. The instruments he used in investigating the 

 minute structures dealt with in his first work to some extent, but 

 more extensively in his subsequent works, were very imperfect. He 

 held " that some things may be demonstrated by reason and the 

 eye jointly, without a glass, which cannot be discovered by the help 

 of the glass ; or else the discovery is so dark that it may not be 

 safely depended upon." A dangerous maxim, and happily abandoned 

 by all careful observers in these days. 



In his account of the germinating seed Grew gave to the descend- 

 ing axis the name of radicle, and the ascending axis he called the 

 plume. He distinguished the cotyledons, and determined that they 

 were leaves from observing that in some plants they spread them- 

 selves in the air. The " seminal roots " which, from animal analogies 

 and the exercise of his "reason," he found in the cotyledons, were, 

 in his judgment, the essential structures, while the somewhat acci- 

 dental cellular tissue was filled in around these organs. He called 

 this tissue parenchyma, because it was " the part through which the 

 inner body is disseminated." 



In his anatomy of the root, stem, and branches he distinguished 

 two different elementary tissues, the one parenchymatous found in the 

 cortex, medullary rays ("insertions " he named them), and the pith ; 

 the other the " lignous," with its vessels and fibres which are always 

 elongated in the direction of the axis, whereas the parenchyma is 

 " extended much alike both in the length and breadth " of the axis. 

 This was very near to an accurate definition- of what is now called 

 parenchyma and prosenchyma. He quotes with approval Hooke's 

 observations. " Mr. Hooke," he says, " sheweth us that the pores of 

 the pith, particularly of elder-pith, so far as they are visible, are all 

 alike discontinuous ; and that the pith is nothing else but an heap of 

 bubbles." And he adds that this observation of Hooke's " confirms 

 what in the second chapter we have said of the pith and cortical 

 body, and of the sameness of both their natures with the parenchyma 

 of the seed. For, upon farther enquiry with better glasses, 1 find 

 that the parenchyma of the plume and radicle, and even of the lobes 

 (cotyledons) themselves, though not so apparently, is nothing but a 

 mass of bubbles." To Hooke undoubtedly belongs the discovery of 

 the vegetable cell, and Grew's difficulty in fully accepting this dis- 

 covery arose from his conviction that the parenchyma of the pith, 

 medullary rays, and bark was a medium of circulation, aud the 



