46 LIFE OF ELIE METCHNIKOFF 



led him to suppose that the Nematodes (of the worm 

 tjipe) formed an independent group ; he now pro- 

 posed to settle that question. Leuckart allowed him 

 to work in his laboratory during his absence for the 

 holidays ; Elie immediately set to work and dis- 

 covered a very curious and quite novel case of alter- 

 nation of generations; hermaphrodite and parasitic 

 Nematodes giving birth to a free bisexual generation. 



Delighted with his discovery, he hastened to com- 

 municate it to Leuckart, who was incredulous at first 

 but had to give way to evidence when Elie showed 

 him all the intermediary stages. Still the German 

 scientist was obviously annoyed that this discovery 

 should have been made in his absence and inde- 

 pendently from him. He proposed to the young 

 man that they should continue researches in colla- 

 boration and publish a joint memoir. Elie accepted 

 joyfully. In his ardour he worked too much, and 

 fatigued his eyesight so that he was forced to limit 

 his microscopical researches to a few hours a day, and 

 Leuckart advised him to take a rest. 



It happened that Elie's brother Leo had just settled 

 in Geneva and invited him to stay with him ; Elie 

 started to join him. The brothers had not met for a 

 long time. Leo had been travelling and had resided 

 in many different places. He was an extraordinarily 

 gifted man, impulsive, brilliant, and artistic, but rest- 

 less and incapable of adhering to a steady course of 

 action ; he scattered his activities and did not there- 

 fore produce all that his rich nature was capable of. 

 He had a remarkable gift for languages ; he knew not 

 only a number of European languages but also several 

 Oriental languages, having been in the East, where he 

 had occupied a post of agent in navigation and com- 



