436 LEADING AMERICAN MEN OF SCIENCE 



He found the accepted views of great European authorities were 

 not correct, that they had not seen all there was to be seen and had 

 hence made false inferences. Though he says "this was my first 

 effort in the field of Marine Zoology" the results were of great 

 importance. 



To understand his interest in Salpa and the peculiar way his 

 mind worked upon its problems we must recall first that it is one 

 of the quiet bag-like creatures, the Tunicates, whose embryology 

 had shown them to be essentially like, and hence in the new views, 

 blood relations of, the Vertebrates: and second that it was first in 

 Salpa that the remarkable phenomenon of "alternation of genera- 

 tions" had been extended to animals. 



So great was the interest in Europe in those problems centering 

 in the Tunicates that Brooks defends his first publication of his 

 results without all his evidence in illustrations, by the remark that 

 students of Salpa were finding new facts so rapidly that one who 

 held back his discoveries till his illustrations should be printed 

 might well find his discoveries no longer new. 



It was the poet-naturalist Chamisso who in voyaging around the 

 world with Kotzebue, deduced for Salpa, in 1814, the phenom- 

 enon of "alternation of generations." This was universally 

 accepted and Salpa was described as having two generations or 

 different successive individuals with different modes of reproduc- 

 tion in each life-cycle. That is, there were solitary Salpas and 

 chain Salpas found in the water, and the solitary ones were seen 

 to make the chains of individuals by a budding or a non-sexual 

 process. The individuals of the chains, however, had eggs and 

 sperm and gave birth to solitary Salpas having a true sexual origin, 

 but themselves again sexless. Thus there was said to be an alterna- 

 tion of sexless and of hermaphrodite individuals and a sequence 

 of non-sexual and of sexual modes of generation. 



Brooks found the same facts but, in addition, the real origin of 

 the eggs not in the chains but in the solitary individuals, which 

 not only budded forth the chains but put an egg into each individ- 

 ual of the chain. 



Hence he claimed then that there was no true alternation of 



