XIV 



thus be looked upon as the precursors of C. E. Baer, whose classical 

 researches on the genesis of the ovum in the Mammalia and in man 

 appeared in 1827. 



Simultaneously with their researches on blood and fecundation, 

 Prevost and Dumas published several other physiological investiga- 

 tions not immediately connected with the main subjects of their 

 studies. The urine and the organs of secretion of frogs successively 

 engaged their attention. They also studied the phenomena accom- 

 panying the contraction of muscular fibre. 



Lastly, Prevost and Dumas' suggestion as to the treatment of 

 stone by electricity should not be left unnoticed. Their experiments 

 showed that the current of a powerful battery is capable of destroying 

 and dissolving the phosphatic calculi of the bladder, without its 

 mucous membrane being materially affected. Although, at a sub- 

 sequent period, these researches were continued and materially 

 enlarged by the late Dr. Bence Jones, the author of this sketch 

 has not been able to learn that the treatment indicated by these 

 remarkable results has been successfully applied in surgery. 



At this period, i.e., in 1822, Dumas might have settled at Geneva, 

 and many circumstances led him to think seriously of doing so. An 

 incident, however, which happened at that time, and which at first 

 sight seemed in no way likely to influence a well-matured plan of 

 life, induced hiru within a few days to change his mind. He made 

 the acquaintance of Alexander von Humboldt, who invited him to be 

 his companion during a few days' stay at Geneva. The short inter- 

 course with this extraordinary man suddenly expanded his aspira- 

 tions. 



The memorable hours he had spent with him had opened a new 

 world to his mind. He had been more especially impressed with 

 what he had told him of Parisian life, of the happy collaboration of 

 men of science, and of the unlimited facilities which the French 

 capital offered to young men wishing to devote themselves to scientific 

 pursuits. He began to think that Paris was the only place win re 

 under the auspices of the leaders of physical and chemical science, 

 with whom, he had no doubt, he should soon become acquainted, he 

 might hope to find the advice and assistance which would enable him 

 to carry out the labours over which he had been pondering for some 

 time. His mind was soon made up he must go to Paris. 



Dnmas' removal to Paris, which took place in 1823, brought the 

 physiological labours in which he had been engaged along with 

 Prevost to a conclusion. Though the separation from a friend, with 

 whom he had been in daily intercourse for so many years, must have 

 been deeply felt by the young savant, who had now to steer his course 

 alone, he had the good fortune to become acquainted with three young 

 men of about his own age, with whom he soon entered ioto friendly 



