166 On Absorption. 



especially where thinnest, absorption takes place. By the 

 term absorption, I mean the simple passage of fluids, with- 

 out retardation for the purposes of assimilation or rejection. 



In order to trace the passage of these fluids, I ^have used 

 the aniline dyes, viz., magenta, mauve, blue, green, cerise, 

 and yellow. 



Dr. Roberts, of Manchester, first called the attention of the 

 Royal Society of England, Feb. 18th, 1863, to the wonderful 

 tinting power of magenta, and to the remarkable fact, that 

 if a small quantity be added to a drop of mammalian blood, 

 a minute spot, coloured with the dye, appears at some 

 part of the edge of the disk. Subsequent experiments 

 with tannin resulted in his producing in the red corpuscle 

 of mammals, birds, reptiles, and fishes, "a bright, highly 

 refractive bud or projection on the surface." These he called 

 "pullulations." In the Quarterly Journal of Microscopical 

 Science for July 1863, is ?^. resume oihi^ discoveries. 



I have long since verified all that Dr. Roberts has stated, 

 and have used magenta dye very extensively in histological 

 inquiry. The effect of the direct application of a solution 

 of magenta to a drop of human blood is, besides producing the 

 puUulation in the corpuscle, to colour the nucleus or con- 

 tents of the white corpuscle. These white corpuscles 

 are not all of the same size, some containing a single nucleus, 

 others two, three, four, or more. The lymph corpuscle 

 smaller than the white corpuscle, is also deeply tinged, and 

 there is apparently a transitional form of the lymph cor- 

 puscle towards the white ; and lastly, granular matter 

 deeply tinged. 



The blood of the bird or frog has the nucleus of the red 

 corpuscle deeply dyed, whereas the white corpuscles are 

 uncoloured. 



Moreover, magenta deeply tinges the following elementary 

 structures : 



Corpuscles of lymph and ch^de, contents of duodenal 

 epithelium and mucus. 



Nucleus of all forms of epithelium. 



All young cells. 



Envelope and nucleus of some forms of fat. 



Nucleus of tendon and of unstriped and striped muscular 

 fibre. 



Cell and nucleus of cartilage. 



Cell and nucleus of bone, and of red marrow of bone. 



All forms of nerve cells. 



