Tlie Presidenfs Address. By H. G. Plimmer. 131 



culate, driving it forcibly in to the Arteries, and by its openin<^, 

 giving way for the Blood to come in again out of the Veins." 



Malpiglii had seen the blood-corpuscles, and had mistaken them 

 for fat-cells, and the general idea seems to be that Leeuwenlioek 

 discovered the corpuscles of the blood, but this is really not so ; 

 they had lieen discovered before his time, and he does not speak 

 of it as his own ; but he was the first to descril)e them accurately 

 and differentially. He described the differences between Mam- 

 malian and other corpuscles. He describes the globules of oxen, 

 sheep and rabbits as being of the same kind as those of man, and 

 discovered that the corpuscles of birds, fishes, and the frog were 

 oval and nucleated. He discovered that the colour of blood was 

 due to an accumulation of the corpuscles ; he says : " the matter 

 causing the redness of our blood was constituted of globules" ; and 

 he thought that they must be at least six deep for the blood to appear 

 red. He said the corpuscles were " flexible and pliant," in order 

 that they may get through the capillaries, and he knew that they 

 were heavier than the serum, and that fibrin consisted of " particles 

 of filaments."' He makes the first mention of leucocytes, as those 

 " red globules which, when they are single stuck within to the 

 sides of the glass pipes, and appeared white and colourless." These 

 glass pipes were the first pipettes, and they were the same as we 

 use now ; he sent some of them to the Eoval Societv for their 

 inspection ; and his paper describing their manufacture and use, 

 has only lately been completed by Sir Almroth Wright, whose 

 glorification of the pipette and its modern addition — the teat — is 

 well known. 



He judged very well the relative size of the corpuscles ; very 

 small in Mammals, bigger in Birds, bigger again in Batrachians and 

 cartilaginous Fishes, those corpuscles becoming larger in proportion 

 to the simplification of the organism. 



The blood-corpuscles lead me to mention his attempts to be 

 meticulously accurate about measurements. He is full of images ; 

 he had a predilection for the millet-seed and, later on, blood- 

 corpuscles as standards — the latter, no doubt, recalling to him 

 some of his most interesting work. His real standard was a grain 

 of sand, of the size that 30 would exactly go into an inch ; that is, 

 his grain of sand, which occurs in every paper, is g^ith inch. He 

 had a craze for computations, and, as be says about his Microscopic 

 measurements, he " used a certain number for an uncertain." He 

 was probably as near the mark in doing so, as many are now-a-days 

 who constantly speak m measurements we can form no conception 

 of ; certainly as near the mark as those who measure very con- 

 tractile organisms such as trypanosomes by thousands, and deduce 

 facts therefrom ! He saw bacteria for the first time in the material 

 taken from between the teeth, and he describes and figures bacteria, 

 cocci, and leptothrix. After finding them in his own mouth, 



