72 PROCEEDINGS OF THE AMERICAN ACADEMY 



Museum, and to accompany it with my remarks ; and I delayed my 

 answer to you until I might, with my thanks, send you a coj^y of my 

 article. But when I commenced the work, I saw that the so-called 

 Petronius had besides profane authors used patristic sources, of which, 

 under the article Choirogrylltis, you have yourself given an example. 

 But to trace and investigate the single articles, time was wanting, and 

 I wrote, therefore, to Professor Ritschl, to whom I had already offered 

 my article, of my change of intention, and offered to communicate 

 my copy, in case some one of his pupils should wish to render the 

 fragment accessible to German philologists. An able young philolo- 

 gist in Bonn, Dr. Reifersheid, has undertaken this task, as Professor 

 Ritschl has lately informed me, and in a week, when I shall be again 

 in Greifswalde, I shall send my copy of the Venetian MS. to Bonn, 

 and take care that you receive a copy of Dr. Reifersheid's article. 



Professor Agassiz reiterated his opinion that what are called 

 varieties by naturalists do not in reality exist as such. His re- 

 cent study of the Echinoderms in the collection of the Museum 

 of Comparative Zoology at Cambridge, had confirmed this 

 opinion. He found a great abundance of divergent forms, 

 which without an acquaintance with the connecting ones, and 

 large opportunities of comparison, might be taken for distinct 

 species, but he found that they all passed insensibly into each 

 other. In reply to a question, he stated that he discarded 

 the sterility or fertility of crosses from the tests of the validity 

 of species. 



Professor Parsons suggested that more extended observa- 

 tion might connect the received species by intermediate forms, 

 no less than the so-called varieties. 



And Professor Gray remarked that the intermediate forms 

 connecting, by whatsoever numerous gradations, the strongly 

 divergent forms with that assumed as the type of the species, 

 so far from disproving the existence of varieties, would seem 

 to furnish the best possible proof that these were varieties. 

 Without the intermediate forms they would, it was said, be 

 taken for species ; their discovery reduced them to varieties, 

 — between which, but not between species (according to the 

 ordinary view), intermediate states were to be expected. 



