134 



STRUCTURE AND ENDOWMENTS OF ANIMAL TISSUES. 



completely isolated from one another, and which are consequently just 

 as independent as the vesicles of the Red Snow or other simple cellular 

 Plants. Indeed in the nature of their habitat, we -may compare them 

 with the Yeast-Plant ; for as this will only vegetate in a saccharine fluid 

 containing vegetable albumen, so do we find that these floating cells 

 will only grow and multiply in the albuminous fluids of animals. In 

 their general appearance they very closely correspond with the figure 

 already given as the type of the simple cell. Their diameter is pretty 

 uniform in the different fluids of the body, and even in different animals ; 

 being for the most part about l-3000th of an inch. They are some- 

 times nearly spherical, and sometimes flattened ; when they present the 

 latter shape, they may be made to swell out into the spherical form 

 (see Frontispiece, Figs. 4 and 5) by the action of water, which they im- 

 bibe according to the laws of Endosmose, the thinner fluid, water., 

 passing towards the more viscid contents of the cell, and mingling with 

 them. By the continuance of this kind of action, the cell will be caused 

 to burst. These cells, which are known as the corpuscles of the Chyle 

 and Lymph, and as the White Corpuscles of the Blood, are observed to 

 contain a number of minute molecules in their interior (Front. Fig. 4) ; 



Fig. 19. 



Colourless cells, with active molecules, and fibres of fibrine, from Herpes labialis. 



and at a certain stage of their development, probably that which im- 

 mediately precedes the maturation and rupture of the parent-cell, 

 these molecules may be seen, with a good Microscope, in active move- 

 ment within the cavity. The action of a very dilute solution of potash 

 causes the immediate rupture of these cells, and the discharge of the 

 contained molecules, which are probably the germs of new cells of a 

 similar character. And when they rupture spontaneously, which they 

 are much disposed to do under the influence of contact with air, the 

 fluid which they set free shows an obvious tendency to assume a fibrous 

 arrangement. The cells which are found in many fibrinous exudations 

 resemble the colourless corpuscles of the blood in all essential particu- 

 lars (Fig. 19). Hence it may be concluded that they belong to the 

 same class ; being probably developed from granular germs set free 

 from the blood, along with the matter of the fibrinous exudation itself. 

 215. Besides the cells already mentioned, the blood of Vertebrated 

 animals also contains others, which are distinguished by their red colour 

 and flattened form. These are equally isolated, and lead an indepen- 



