ANATOMY AND PHYSIOLOGY 



OF THE 



VEGETABLE CELL. 



INTEODUCTOEY EEMAEKS. 



If we examine the texture of plants with a powerful microscope, 

 we find that it does not consist, as appears to the naked eye or 

 under slight magnifying power, of a homogeneous substance per- 

 forated by a greater or less abundance of cavities, but is composed 

 of minute portions, of definite form and organization, separable 

 from each other (the elementary organs). 



Observ. Universal as the agreement among pliytotomists has been for 

 some thirty or forty years on this fundamental proposition of vegetable 

 anatomy, it was a long time before it acquired general recognition. 

 The very founders of the anatomy of plants, Leeuwenhoek, Malpighi, and 

 Grew, were, indeed, led by their researches to the detection and distinc- 

 tion of the elementary organs as organized parts, but the real conditions 

 were again misconceived throughout the whole of the eighteenth century. 

 On the one hand, Ludwig and Bdhmer, seeking an analogy with animal 

 cellular tissue, described vegetable cellular tissue as a mass of irregular 

 fibres and lamellae interwoven together ; on the other hand, C. P. Wolff 

 (theoria gemratlonisj described vegetable substance as a homogeneous 

 mass hollowed into holes and canals, a view which still found an active 

 defender durmg the first ten years of the present century, in Brisseau de 

 Mirbel, and is even now held by him to be the condition in the earliest 

 stage of development of vegetable tissue, if not that of the subsequent 

 stages. More correct views were first substantiated by German pliytoto- 

 mists of the present century. 



The primary form of the elementary organ of plants is that of 

 a completely closed, globular, or elongated vesicle, composed of a 

 solid membrane, and containing a fluid (utricle, utriculusj. If 

 this remains still closed after its development is completed, it is 

 called a cell, cellula ; but if a row of utricles arranged in a line 

 become combined, during the course of their development, into a 

 tube with an uninterrupted cavity, through the absorption of their 

 cross walls, a compound elementary organ is produced, — ^the vessel 

 (spiroid of Link), 



Ohserv. The tracing back of the whole of the elementary organs to 

 the primary form of the utricle, has been accompHshed only quite recently. 

 The earlier phytotomists, who took the elongated cells for long tubes, 

 overlooked their analogy with the short cells, believing that they were 

 rather to be compared with the vessels, and they described them as a 

 special anatomical system under different denominations (fibres, lympha- 

 tic vessels, &c.), in which error they were followed even by Treviranus 



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