ALEXANDEE AGASSIZ — MAYEB. 457 



Upon returning from South America, his embryological studies 

 were resumed at Newport, and the development of flounders and 

 other young fishes interested him especially. It was well known 

 that in the young flounder the eyes are on both sides of the head and 

 that after the fish falls over on one side, the eye of the lower side 

 travels around and comes to lie beside its fellow on the upper side 

 of the fish, but Alexander Agassiz discovered that in the transparent 

 young of flounders allied to the Plagusise the lower eye actually 

 penetrates through the tissues of the head and reappears on the sur- 

 face of the upper side of the fish. 



In the young of other bony fishes he discovered a caudal lobe 

 showing that in an early stage the tails of the bony fishes resemble 

 the adult tails of the more ancient ganoids. 



He also found that under the skin of flounders there are yellow, 

 red, and black pigment cells and that changes of color are due to the 

 independent expansion or contraction of these several cells; and in 

 1892 he made the interesting discovery that if young flounders be 

 placed for six weeks in aquaria with white surroundings they lose 

 nearly all color and do not regain their normal color, even if at the 

 end of this time they be surrounded by black. 



These studies of fishes, begun in 1875, were continued for many 

 years in the intervals between expeditions, the last of the series being 

 published in 1892. One of the most important papers of this series 

 appeared in 1878 and is upon the development of that archaic fish 

 the gar pike, Lejndosteus. 



But of all animals the echinoderms interested him most deeply. 

 Indeed of the 1-15 most important scientific papers of which he was 

 sole or joint author 45 treat of echinoderms. Accordingly^ in 1871—77 

 we find him actively engaged in their study. In 1874 he announces 

 the discovery that hybrid larvse may be produced by artificial means 

 between the two common species of star fish of the New England 

 coast. In 1876 he studied the structure of some viviparous echini 

 from the Kerguelen Islands, and found that they habitually carried 

 tlieir young about with them until the young had acquired most of 

 the characters of the adult. In 1877 his beautifully illustrated work 

 upon North American star fishes was published. 



In 1876 he was keenly interested when he visited Sir Wyville 

 Thomson in Scotland and inspected the vast collections of deep-sea 

 forms brought home from the three-years' cruise of the Challenger; 

 and it was a happy moment for him when in 1877 an arrangement 

 was perfected with the United States Government by virtue of the 

 terms of which he was given the scientific direction of the United 

 States Coast Survey steamer Blake during the entire time of her pur- 

 posed explorations of the West Indian and Gulf Stream region. He 

 joined the Blake at Habana, Cuba, in December, 1877, and remained 



