26 ORGANISED FLUIDS. 



investing membrane, and thus distends and modifies its form. 

 Lastly, when a reverse disposition of the fluids exists, a con- 

 trary effect becomes manifested ; exosmosis is the result ; 

 which implies the escape of a portion of the contents of the 

 vesicle into the medium which surrounds and envelopes it. 

 The operation of these principles are beautifully seen, not 

 merely in the blood globules, but more especially in those 

 exquisitely delicate formation^, the pollen granules. 



Between the density of the liquid contained within the 

 red globules, and that of the liquor sanguinis, in states of 

 health, a nice adaptation or harmony exists, whereby these 

 globules are enabled to retain their peculiar form, There is, 

 however, scarcely any other fluid which can be applied to 

 the globules which does not, more or less, affect their shape, 

 most of the reagents employed in their examination rendering 

 them spherical. (See Plate I. Jig. 3.) 



From the preceding observations, therefore, it follows that 

 the red globules, to be seen in their normal condition, should 

 be examined while still floating in the serum : they are best 

 obtained by pricking the finger with a needle or lancet. 



Usually, when the microscope is brought to bear upon 

 the object-glass, the globules are seen to be scattered irre- 

 gularly over its surface, the majority of them presenting 

 their entire disc to view, others lying obliquely, so as to 

 render apparent the central depression, and others again 

 exhibiting their thin edges. (See Plate I. fig. 1.) Not un- 

 frequently, however, a number of corpuscles unite together 

 by their flat surfaces, so as to form little threads, comparable 

 to strings of beads, or of coins, which are more or less curved, 

 and in which the lines of junction between the corpuscles are 

 plainly visible. These strings of compressed globules bear 

 also a close resemblance to an Oscillatoria, and a still closer 

 likeness to the plant described in the history of the British 

 Freshwater Alga3, under the name of Hcematococcus Hooker- 

 iana. (See Plate I. fig. 4.) The cause which determines 

 this union of the cells still requires to be explained, and 

 would seem to be referable to a mutual attraction exerted 

 by the globules on each other. Andral asserts that when 



