i6o 



Louis Agassiz. 



found in the end that, so far from being accumu- 

 lated by the sea, the drift of the Patagonian low- 

 lands has been worn away by the sea to its present 

 outline, like the northern shores of South America 

 and Brazil. ..." 



The Hassler sailed December 4, 1871, and the 

 moment the prow of the good ship entered the Gulf 

 Stream the ardent naturalists were at work ; Count. 

 Pourtales on the temperature of the Gulf Stream, 

 and Agassiz on the fauna of the floating weed known 

 as sargassum. One of the finds was a curious nest — 

 a mass of sea-weed bound in and about and held in 

 place by a delicate cord of gelatinous appearance. 

 The leaves or fronds of the weed were dotted with 

 white eggs the size of a pin's head, and Agassiz soon 

 decided by the use of his glass that each egg held 

 a little fish. But what fish? The parent had not 

 been found with the nest. Agassiz soon bethought 

 him of his previous studies with the pigment cells of 

 fishes, and the first comparison he made satisfied him 

 that the embryos were the young of a Chironectes, 

 young specimens of which he used for comparison. 



It will be remembered that in a letter written 

 to Professor Peirce previous to sailing Agassiz ex- 

 pressed the belief that he should discover some early 

 forms of star-fishes ; it so happened that at the first 

 haul of the dredge off St. Thomas they took stemmed 

 crinoids which seemed like the ghosts of by-gone 

 days rising from the depths of the sea to remind 

 them of the past. One of the crinoids was kept 

 alive nearly an entire day, and Agassiz had an op- 

 portunity to observe its motions, seeing it fold and 



