ALEXANDER AGASSIZ 431 
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 Alex- 
ander Agassiz discovered that in the transparent young of flounders 
allied to the Plagusie the lower eye actually penetrates through the 
tissues of the head and reappears on the surface of the upper side of 
the fish. 
In the young of other bony fishes he discovered a caudal lobe show- 
ing 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 archeic fish the 
gar pike, Lepidosteus. 
But of all animals the echinoderms interested him most deeply. 
Indeed of the 145 most important scientific papers of which he was sole 
or joint author 45 treat of echinoderms. Accordingly in 1874-77 we 
find him actively engaged in their study. In 1874 he announces the 
discovery that hybrid larve may be produced by artificial means be- 
tween the two common species of starfish gf the New England coast. 
In 1876 he studied the structure of some viviparous echini from the 
Kerguelen Islands, and found that they habitually carried their young 
about with them until the young had acquired most of the characters of 
the adult. In 1877 his beautifully illustrated work upon North Amer- 
ican starfishes 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 per- 
fected with the United States government by virtue of the terms of 
which he was given the scientific direction of the U. 8. Coast Survey 
steamer blake during the entire time of her purposed explorations of 
the West Indian and Gulf Stream region. He joined the Blake at 
