116 ALEXANDER AGASSIZ 



were in reality the young state of certain marine worms 

 known as Balanoglossus. 



He was also much occupied in the study of the em- 

 bryology of various jelly-fish. The following quotation 

 from his publication on this subject is interesting as 

 showing his attitude toward evolution at this period. 

 Speaking of Haeckel's Gastraea theory, he says : " If we 

 need an ancestor for our phylum why not at once go 

 back to the cell? There we have a definite starting 

 point, a typical element which underlies the whole of 

 the animal kingdom and which forms the walls of 

 Haeckel's gastrula. Then we shall all be agreed and 

 when we frankly state that all organisms are derived 

 from a primitive cell and from its subsequent increase, 

 we come within the range of positive knowledge, but 

 we are unfortunately as far as ever from having for 

 that reason been able to trace a mechanical cause for 

 the genetic connection of the various branches of the 

 animal kingdom." ' 



TO A. MILNE EDWARDS 



Cambridge, Mar. 17, 1871. 

 We have just heard that communication has been 

 reestablished, and I seize the first opportunity to write 

 you a few lines and to ask for news of yourself, your 

 father, and of all the gentlemen of the Jardin des 

 Plantes, who were so kind to me during my stay in 

 Paris. I much regretted not being able to pass through 

 Paris to say good-bye before my departure. In Switzer- 

 land I hoped up to the last moment that peace would 

 be declared, and that I should not be forced to leave 



1 "Embryology of the Ctenophorae," Mem. Am. Ac, vol. x, no. 3, 

 p. 382. 



