134 Transactions of the Society. 



abstracts of general microscopical work in our Journal ; so I am 

 bound to fall back on my own work, and to try to engage your 

 consideration, contagiously within the limits of my own, on some 

 of the things with which I am personally interested, say " On 

 certain blood parasites." I cannot, alas, offer you a complete 

 scientific account of the things I shall talk about and show to you, 

 because they and their subject are quite new, and our science of 

 them is as yet all in scraps and tangles ; and it will probably be 

 very many years before we can know the complete history of these 

 organisms which are parasitic in the blood. So you must accept 

 these words of mine as you would if you had strolled into my 

 workshop and had asked me to show you what 1 was doing, and to 

 tell you somewhat of the things I should show you. I have one 

 excuse for talking of this part of my own work, and that is that it 

 is entirely microscopical, and so has a place here. 



Parasites in general have been known for ages ; there are re- 

 cords of them five centuries before our era, but the knowledge of 

 the parasites of the blood, depending on an exact use of the Micro- 

 scope and on elaborate methods, dates really only from 1880, when 

 Laveran, in the military hospital at Constantine, discovered the 

 hsematozdon of malaria. No scientific instrument has ever been 

 so unscientifically misused and abused as the Microscope — you 

 have only to visit our laboratories to-day, even, to be assured of 

 this — but this discovery of Laveran's was due to the intelligent 

 use of the Microscope in disease, as was Pasteur's great work on 

 the silkworm disease, and Lambl's discovery of amoebse in certain 

 dysenteric conditions which immediately preceded it. Laveran's 

 great discovery opened new ways, new methods of research, the 

 far-reaching results of which we cannot yet see. We know to-day 

 that, besides being the cause of malaria in all its forms, the Pro- 

 tozoa are the cause of recurrent fever, of syphilis, of dourine, of 

 nagana, of trypanosomiasis and sleeping-sickness, of Texas fever, 

 of tropical splenomegaly or kala-azar, of the several coccidioses of 

 man and animals, and of aracebic dysentery ; and we believe that 

 they are the cause of other diseases of man and animals, which our 

 colonial expansion is now driving us to study more closely. These 



EXPLANATION OF T'LXTE^— continued. 



stages of the parasite, c is a later stage, d d still later stages, when 

 the whole erythrocyte is filled with the parasites, e a later stage, 

 with vacuolation. / a parasite, probably degenerating, free in the 

 blood. 

 Fig. 6. — Haemogregarines in the blood of a Eat-tailed Serpent, x 450. a parasite 

 inside erythrocyte, h parasites with only the nucleus of the host-cell 

 attached to them ; the hcemogregarines are very granular, and the 

 nuclei active. 

 ,, 7. — Hffimogregarines in the blood of a Texan Rattle-snake, x 230. a parasites 

 inside the erythrocytes, b free forms. 



/ 



