xxxii Appendix. 



to say any more about them, than that they satisfied him that not only cells 

 from the vaccine pock would live and grow in the serum of blood, but that 

 the red corpuscles of the blood itself would grow and reproduce themselves 

 outside the living body under favourable conditions, and if supplied with a 

 suitable pabulum. These experiments were made in the following manner :• 

 A small clot from fresh blood, which had coagulated sufficiently long for some 

 serum to exude, was placed in a small glass bottle. The clot usually occupied 

 from l-5th to l-6th of the bottle, the remainder was filled by the serum of the 

 same blood, and the bottle carefully closed so as to leave no air between the 

 cork and the contents. Particular attention was paid to this point at first, 

 from the fear that putrefaction would occur if air were allowed to enter. It 

 has since been found that a small quantity of air does not produce putrefac- 

 tion, and that the bottles may be opened again and again, and their contents 

 examined, without any fear of such a result. The larger sized vaccine tubes 

 may also be used. The first effect of putting the serum on the clot was that 

 the former was immediately reddened by the diffusion of red corpuscles 

 through it. And it will be found that serum thus reddened if put in a cold 

 place requires several hours — twelve at least — before it becomes perfectly 

 colourless again. The necessary movements of corking the bottles, etc., 

 invariably produce a deep reddening of the serum. The first change percep- 

 tible to the naked eye when the bottles thus charged have been subject for 

 about three hours to the heat of the human body is that the red corpuscles 

 separate very readily from the serum, and form a stratum at the most 

 depending part of the bottle. At the same time they lose their red tint and 

 become lake coloured. If shaken up, so as to mix intimately with the serum, 

 they very quickly fall down again, and in a few minutes the serum is quite 

 clear of them — as far as the naked eye can see. It looks tinted but is not red. 

 Thus it is evident that the red corpuscles have changed their colour, and have 

 become, relatively to the serum, of a greater specific gravity, or they would 

 not so readily subside. It is not established whether the serum has 

 diminished in gravity, or the corpuscles have gained. One thing is certain, 

 that they subside very quickly. 



While these changes are going on some kind of gas is formed, as, however 

 carefully the air may have been excluded, a small bubble is always found. In 

 one series of experiments, in order to make certain that no air had got in 

 accidentally, the tubes were closed with melted wax, but the air bubble always 

 appeared. Under the microscope it was apparent that "the red corpuscles 

 were dividing by budding and fissure. Many are elongated and oval, others 

 are nearly divided ; there are many small circular bodies of same colour as 



the red corpuscles, but much smaller." This is copied from notes taken at the 

 time. 



