THE CONNECTIVE SUBSTANCE GROUP. 67 



a delicate envelope, 5, which appears to be highly elastic, so 

 that it will stretch or relax, according as the networks are 

 compressed or dilated. By teasing with needles or immersion 

 for a few days in a 10 per cent, watery solution of common 

 salt, these corpuscles can often be separated from the bundles, 

 and then they will be seen to form a connected system. When 

 entirely isolated from one another, they often appear spindle- 

 shaped. That this is not their character may be shown by 

 passing a current of fluid through the specimen a method 

 already described under the name of irrigation. It is accom- 

 plished in this way : having affixed small strips of filter-paper 

 to the edges of the cover on either side, and moistened one side 

 with fluid, the excess will be absorbed by the other slip, caus- 

 ing a current by which the corpuscles may be made to roll 

 over. We then learn that they are disks of an irregularly 

 flattened form, having longer or shorter processes (c, c, Fig. 

 25) variations in form which seem to depend, in a great 

 measure, upon the tension to which they are exposed, and the 

 position they occupy in the tissue. This explanation will 

 serve to show why all measurements of such corpuscles are 

 merely approximative, and have but little value. 



They are shrunken by immersion in alcohol, swollen by the 

 imbibition of water, are drawn out into long, flattened spindles 

 when the tissue is put on the stretch, or become rounded, per- 

 haps nearly spherical, during relaxation. They may assume 

 almost any form as the result of pressure. 



The nucleus may be regarded as more of an exception to 

 this rule ; at any rate it seems that in fresh specimens, when 

 the substance has been swollen by immersion in water, it is 

 always oval and flattened. 



The bundles upon which these bodies lie are somewhat 

 cylindrical in form, branched, and composed of separate fila- 

 ments, that can be separated by Mueller's fluid, or a 10 per 

 cent, waterj'' solution of common salt. 



Two other forms of corpuscles may also be noticed : (1) the 

 kind observed by Waldeyer, and called plasma cells, and 

 thought by him to be corpuscles peculiarly prone to take up 

 fat to make fat tissue, bodies four or five times the size of 

 a lymphoid corpuscle, and rounded in form, containing a cen- 

 tral body ; and (2) the ordinary lymphoid corpuscles, seen at 

 times in all tissues. 



