

xni 



renewed study of the blood, and they were soon able to publish a 

 paper upon this subject. This appeared in the " Bibliotheque Uni- 

 verselle de Geneve," and in the title Dumas still figures as Eleve de 

 Pharmacia. The results arrived at by the young inquirers for a 

 long time satisfied the wants of science, and if our knowledge of the 

 blood has been considerably expanded by many subsequent observers, 

 the experiments of Prevost and Dumas have invariably served as a 

 starting point for these inquiries. 



It was about that time that the death of Princess Charlotte had 

 excited a feeling of sorrow all over Europe. The pathological pro- 

 blem presented by this sad event induced the two experimentalists to 

 resume the study of the transfusion of blood. This problem has 

 since been frequently examined, but these renewed inquiries have 

 added but little to the knowledge elicited by Prevost and Dumas' 

 researches upon the subject. 



A very important result at which they arrived was, moreover, the 

 demonstration of the presence of urea in the blood of animals the 

 kidneys of which had been removed. They inferred from this 

 observation that the function of the kidneys is not to produce but to 

 eliminate urea formed in the blood. Their experiments have been 

 repeated by the most distinguished observers, among whom it suffices 

 to name Gmelin, Tiedemann, and Mitscherlich, and the conclusions 

 to which they led are therefore generally adopted by physiologists. 

 We should not, however, leave it unmentioned that, during the last 

 few years, some dissenting voices have been heard, and that some 

 modern physiologists believe they have proved that urea is also gene- 

 rated by the kidneys. But if it should ultimately be proved, beyond 

 doubt, that the kidneys, like many other organs, more especially the 

 liver, have the power of producing urea, elimination of urea formed 

 elsewhere would be still the principal function of the kidneys, 

 although not the only one, as Prevost and Dumas have been led to 

 believe from their experiments. 



From the researches on blood Prevost and Dumas proceeded to the 

 examination of the phenomenon of fecundation, the knowledge of 

 which they considerably expanded. It deserves more especially to be 

 noticed that, notwithstanding some previous observations by Swam- 

 merdam and Spallanzaui upon the subject, modern physiologists are 

 unanimous in recognising Prevost and Dumas as the discoverers 

 of the phenomenon of segmentation in the ovum of the Batrachians. 

 At the same time these investigators observed that at a certain 

 stage of fecundation there escapes from the ovary of the Mammalia 

 a limpid almost microscopic vesicle which enters the Fallopian 

 tube, and proceeds to the uterus, where, when impregnated by the 

 spermatozoids of the male, it is fixed, and, increasing in size and 

 development, gives rise to the foetus. Prevost and Dumas must 



