CHAKACTEKS OF PUS. 191 



their size varies, on account of their endosmotic properties, with the 

 specific gravity of the pus-serum, they being contracted and smaller 

 as the latter increases, and vice versa (p. 145). 



The investing membrane sometimes wanting in the smaller cor- 

 puscles ( WedT) is an albuminous ("proteine") compound, but is not 

 fibrine. (Lehmann.) 



The nuclei of pus-corpuscles are 3^35 to ffaj of an inch in dia- 

 meter ( WedT), and also appear to be an albuminous substance. If 

 they had been originally visible, they are usually of a lenticular 

 form, and these are probably the mature corpuscles. In case they 

 are invisible at first, they are subsequently found to be tripartite, 

 and of a sharply- defined outline. This latter appearance, usually 

 produced by a change -in the chemical reaction of the pus after its 

 formation, has been thought to be characteristic of pus-corpuscles. 

 It has. however, been already explained (p. 146). 



The contents of the pus-corpuscles are also principally albuminous 

 compounds. (Lehmann.) The fat of pus (20 to 60 parts in 1,000) is 

 contained, in great part (about two-thirds), in the corpuscles ; and the 

 granules are probably composed of it, in part at least. 



In regard to the precise manner in which pus-corpuscles are 

 formed, nothing special need be remarked here, they being deve- 

 loped from minute granules into larger corpuscles the nuclei as 

 Yogel has shown, and around which the cell- wall subsequently ap- 

 pears; it being at first transparent, and afterwards granular. They, 

 like all other cytoid corpuscles, are first formed by free cell-develop- 

 ment. But they may, doubtless, be subsequently developed from 

 the pre-existing corpuscles, and thus pus propagates itself. Hence 

 the importance of seasonably evacuating a cavity containing pus ; 

 or of destroying the pus-corpuscles, as by the application of caustic, 

 &c., as in the treatment of ophthalmia and blennorrhoea. 



It is a practically important question, How long a time is neces- 

 sary for the development of pus in a fresh exudation? Lehmann 

 states that in exudations "not perfectly fresh, obtained from subcu- 

 taneous wounds with loss of substance," in the lower animals, 

 granules and nuclei, constituting the beginning of the suppurative 

 process, appear in "about half an hour." Grluge says that in "twelve 

 hours after a blister is applied to the surface of the human body, 

 the exudation has become slightly turbid from the presence of pus- 

 corpuscles, many of which already have a clear border to one-half 

 of their circumference, which is the future cell-wall in the course 

 of development." The process of development still continues, even 

 if the exudation be removed from its contact with the body. In- 

 deed, in the clear exudation, when removed from the surface, "per- 

 fectly spherical cells with nuclei were developed after several hours" 

 (p. 46). Helbert had before asserted that cells may form in a plastic 

 liquid removed from the body. 



In the case of a blister, we may, therefore, conclude that true pus 

 may be formed in less than twenty -four hours. A longer time, 



