Seeing and Not Seeing the Large Cells. 23 



of venom in - 7 per cent. NaCl. with the canula in the 

 vein, by a piece of rubber tube, the calibre of which 

 was controlled by a screw clamp. With this arrange- 

 ment I have been able to introduce large doses (0'005 

 gramme per kilo), and yet only produce inhibition of 

 the coagulability of the blood. The discovery that the 

 effects on the blood, after slow injections, are vastly 

 different from, in fact exactly opposite to, those follow- 

 ing rapid injection of the venom, explains why, in my 

 earliest experiments, I did not obtain the same fluid 

 condition of the blood as Halford, who used either 

 subcutaneous injection of the venom, or else allowed 

 a snake to bite the dog. By these methods delivery 

 into the circulation would necessarily be slow, and 

 comparable with results obtained by intravenous 

 injection, only in cases in which such injection was 

 very gradual." 



Seeing and Not Seeing the Large Cells in 

 the Blood. 



In 1891, I called on Sir J. Fayrer in London, and 

 told him I wished to show him the cells in the blood. 

 He received me very courteously, but said that he 

 knew little about the microscope, and had trusted to 

 the statements of Drs. Macnamara and Lewis the 

 latter gentleman, the whole medical world knows, from 

 his description of the blood of Hindoos abounding 

 with those remarkable embryos " the filaria sanguinis 

 hominis." Here there could be no doubt as to the 

 capacity of the microscopic observer. 



I then visited my old friend Mr. Bartlett, Superin- 

 tendent of the Zoological Gardens, London, and got 



c 2 



