132 



ON THE ELEMENTARY PARTS OF THE HUMAN FABRIC. 



Fig. 30. 



The Colourless corpuscles, indeed, often show a disposition to adhere to the 

 walls of the vessels ; which is manifestly increased on the application of an 

 irritant. Hence the idea naturally arises, that (to use the words of Mr. Whar- 



ton Jones) " there is some reciprocal re- 

 lation between the colourless corpuscles, 

 and the parts outside the vessels, in the 

 process of nutrition." What that rela- 

 tion is, we shall now proceed to inquire. 

 153. In regard to the purpose of the 

 Colourless corpuscles in the Animal eco- 

 nomy, a view has been brought forward 

 by the Author,* which increased consi- 

 deration has only served to strengthen ; 

 and which he advances here, with some 

 degree of confidence that it will be found, 

 on attentive examination, warranted by 

 a large number of physiological analo- 

 gies, though not capable of being direct- 

 ly proved. That it may be rightly un- 

 derstood, a general sketch of certain 

 known operations of cells in Plants and 

 Animals will be first given. It is not 

 difficult, on taking a comprehensive sur- 

 vey of the Assimilating processes, to 

 find a number of examples, in which 

 cells are developed in a temporary man- 

 ner ; growing, arriving at maturity, and 

 then disappearing, apparently without having performed any particular 

 function. In the albumen of the Seed, for instance, this often takes place to 

 a remarkable extent. In the Yolk of the Egg, there is a similar transitory 

 development of cells, of which several generations succeed each other, without 

 any permanent structure being the result ; and we have seen that, according 

 to Dr. Barry ,t a process of the same nature takes place within the germinal 

 vesicle, and in the primary embryonic cells and their descendants ( 130). 

 It can scarcely be imagined by the well-judging Physiologist, that all this 

 cell-life comes into existence without some decided purpose ; and if we can 

 assign to it an object, the fulfilment of which is consistent with the facts sup- 

 plied by analogy elsewhere, this may be reasonably considered as having a 

 fair claim to be received as a physiological induction. In all these instances, 

 and in many more which might be quoted, the crude alimentary materials are 

 being prepared to undergo conversion into permanent and regularly-organized 

 structures. We have seen that the very first union of the inorganic elements, 

 into the simplest proximate principles, is effected by the cell-life of Plants. 

 The change of these principles into the peculiar compounds, which form the 

 characteristic secretions of Plants, is another result of their cell-life. And 

 there seems equal ground for the belief that the change of these proximate 

 principles into the peculiar glutinous sap, which is found wherever a forma- 

 tion of new tissue is taking place, is equally dependent upon the agency of 

 cells. Thus, the starchy fluid, which is contained in the ovule previously to 

 its fecundation, is probably not in the state in which it can be immediately 

 rendered subservient to the nutrition of the embryo ; and the development of 

 successive generations of cells, which exert upon it their vitalizing influence, 



A small venous trunk, a, from the Web of 

 the Frog's foot, magnified 350 Diam ; fc,A, cells 

 of the pavement-epithelium, containing nuclei. 

 In the space between the current of oval blood- 

 corpuscles, and the walls of the vessel, the rouud 

 transparent white corpuscles are seen. 



* Report on Cells, in British and Foreign Medical Review, Jan. 1843. 

 | Embryological Researches. Third Series. 



