1863.] 485 



for magenta used in the arts) was employed ; and some advantage 

 was found therein. When a solution of tannin, of 3 grains to the 

 ounce of water, was added to blood that had already been dyed with 

 magenta, it was found that the parietal maculae had their colour 

 intensified, and that they became more conspicuous objects. The 

 investigation was, however, not pushed any further in this direction, 

 for it was found that tannin alone produced an even more remarkable 

 effect than magenta. To this effect I now desire to draw particular 

 attention. 



When a solution of tannin, of the strength of 3 grains to the 

 ounce, was applied to human blood, or to that of the horse, ox, 

 sheep, pig, or cat, the blood immediately became turbid ; and when 

 a drop was placed under the microscope the corpuscles were found 

 greatly changed, as represented in fig. 2. 



Fig. 2. 



Human blood after the action of tannin. 



a. Double pullulation. 



b. b. Hooded modification. 



c. Outline of the cell seen continuously through the pullulation. 



d. Bursting of the pullulations independently of destruction of the cell. 



Each corpuscle appeared to have thrown out a bright, highly re- 

 fractive bud or projection on its surface. The projections were 



