340 



severe attack of yellow fever, in preference to the blood-serum, was made 

 in consequence of the idea that I would thus introduce into the system of 

 the inoculated person, not only the immunizing substances contained in 

 the liquid serum, but also a considerable number of live leukocytes, which, 

 under the circumstances, ought to be endowed with the faculty of elabora- 

 ting antitoxins whenever they should come into the presence of yellow- 

 fever germs or their toxins. Now, if these specialized leukocytes could be 

 -made to live and prosper in the system of the inoculated subject, they 

 might be expected to multiply by segmentation of their nuclei or by kar- 

 yokinesis, and to transmit to their descendants the antitoxic properties 

 with which they were endowed, whereby a more effective and more lasting 

 protection might be secured than would result from the blood-serum ino- 

 culation, i) 



1 have every reason to regret that the closing of the Havana military 

 hospitals to civilians during the last three years, and the difficulty of 

 obtaining further information about my 13 artillerymen, have prevented 

 me from completing this interesting investigation. So far as it went how- 

 ever, the result proved satisfactory, and I am happy to be able to adduce in 

 support of my method the high authority of Professor Roux, of Paris, 

 who favored me with the following reply to a letter requesting his opinion 

 about the soundness of my views : — 



Institut Pasteur, 25 rue Ducrot, 



Paris, 1. Decembre, 1894. 

 Monsieur et honoré Confrere: — 



L'idée que vous mettez en avant á propos de la sérosité de vésicatoires 

 est parfaitement fondee. Chez les animaux immumisés contre le tétanos et 

 la diphtérie la sérosité de 1 'cédeme et des vésicatoires ont les mémes pro- 

 priétés que le serum. M. Vaillard a fait á ce sujet des experiences tres pro- 

 bantes avec les animaux immunises contre le tétanos. Je vous souhaite 

 bonne chance dans vos essais dans la fiévre jaune et serai tres heureux de 

 les connaítre. 



Reeevez, Monsieur et honoré confrere, mes salutations empressées. 



Dr. Roux. 



1) Some years ago, Dr. Geo M. Sternberg, on examining a sample of yellow-fever 

 blister serum that I had collected several hours before in a glass bulb, was struck by the 

 fact that the leukocytes were still alive and showed active ameboid movement. I have 

 since, on several occasions, verified the fact with specimens of the serum used in my 

 inoculations. There is, therefore, no reason to doubt that, when the serum is injected 

 immediately after it has been drawn from the blister, the leukocytes may easily adapt 

 themselves to a medium so similar to their former habitat as the subcutaneous tissues of 

 the inoculated person appear to be. 



