ON GROWTH AND EXTENSION IN THE VKGETABLE KINGDOM. 27 



IV.-— On Groioth and Extension m the Vegetable Kingdom. 

 By H. F. Link, M.D., F.M.H.S. 



(Translated from the German,*) 



Vegetable physiology is now in the same state in which human 

 physiology was above two hundred years since. The circulation 

 of the blood from tiie heart back again to the heart was then 

 unknown ; it was even believed that the arteries contained air, 

 and that it was only under peculiar circumstances that any blood 

 penetrated into them. In the same manner we do not yet know 

 through what inner parts of the plant the nutritive matter rises 

 from the earth : some are of opinion that it is through the spiral 

 and other similar vessels, whilst others maintain that these vessels 

 only contain air, because we only see air in them, and that the 

 sap rises through the cellular tissue. So different are the 

 opinions held on one of the most important facts in vegetable 

 physiology. But however this may be, the practical man must 

 direct his attention to these theoretical investigations, were it 

 only to avoid being led astray by them. 



I speak liere only of those plants in which we recognise dis- 

 tinct organs — stem, leaves, and fruits — which I sliall term Pha- 

 nerophytes, because in them everything is open and perceptible. 

 Lichens, therefore, algae, and fungi are excluded, because in 

 these we observe no distinct organs. We may call them Cryp' 

 tophytes, or hidden plants, because in them their whole vegetable 

 being is hidden from us. I should have adopted the well-known 

 distinction between Phanerogams and Cryptogams, were it not 

 that mosses have distinct sexual organs, which are wanting in 

 the much more perfectly developed ferns ; or the division into 

 cellular and vascular plants, but that mosses, with their evident 

 sexual organs, have no vessels. We shall commence with the 

 Phanerophytes ; for we must not, as is usually done, judge of 

 palms from the algae, of the eagle from the earthworm. 



Phanerogamous plants are remarkable in this, that they consist 

 in almost all their parts of membranous cells, round (globular) 

 and angular, elliptical (ellipsoid), cylindrical, and prismatic, 

 containing sap or air. In this respect they differ strikingly from 

 animals, in which the principal parts at least do not consist of 

 such cells. A cellular structure has indeed been found in some 

 parts of animals, and it has been conjectured, not without some 

 grounds, that all parts of animals were originally formed from 

 cells ; but, independently of the circumstance that this is mere 



* The original of this interesting paper is illustrated by microscopical 

 views of various points of vegetable anatomy. The latter having been 

 omitted in this place, the text has been slightly altered in consequence. 



