EXHALENTS. 163 



posed to them, are Prochaska, Mascagni, and Richerand. The 

 leading facts of the former are; The microscopical observations 

 of Lewenhoeck, who speaks of vessels admitting only serous 

 globules; the phenomena of inflammation, which render red, 

 parts naturally white and transparent; the difficulty of con- 

 ceiving how the nourishment of. certain parts can be main- 

 tained, whose capillary system of red blood is so limited, in 

 proportion to points not susceptible of it. The opinion of Mas- 

 cagni and others to the contrary, is: That those exhalents, if 

 they existed, should be seen readily, inasmuch as they are 

 within the range of a microscope, whose powers enable one to 

 examine a body much smaller than a red globule of blood; 

 that injections should penetrate them, instead of being limited 

 to vessels whose existence is sufficiently confirmed by exami- 

 nation in the living state; that if during inflammation they do 

 seem to be injected with red blood, the appearance is delusive, 

 and depends upon the existing capillaries being dilated so as to 

 receive more red blood than usual, upon the formation of new 

 vessels, and upon sanguineous infiltration; and as to mem- 

 branes naturally white, as the conjunctiva, the colour depends 

 upon the capillaries, while in a healthy state, being so small 

 that they do not admit the red globules in a file sufficiently 

 numerous to be perceived by the eye; the globules being, pro- 

 bably, then conducted in a scries of one only, or in a single 

 file, like a string of beads. It is, therefore, much more rea- 

 sonable not to admit the existence of vessels which it is very 

 doubtful whether any one has seen. 



When a watery injection is pushed into a blood vessel, it in 

 a little time shows itself as a fine dew upon the surface of the 

 serous and mucous membranes; in the cellular membrane, and 

 elsewhere. According to many anatomists, it has gone through 

 the system of exhalents, and, indeed, presents itself to sight in 

 very much the same way that exhalation occurs in the living 

 state. From the view which has just been taken, it becomes 

 more probable, that this perspiration is executed through the 

 interstices or pores of the vessels. In the dead state it is merelv 

 a mechanical result, a simple straining of the fluid; whereas, in 

 the living body it is a vital function, continually modified by 

 the peculiar vital powers of the organ or membrane where it 

 occurs; and, therefore, presents itself under the form of the 



