BIOLOGICAL LABORATORY AT NAPLES 



is particularly seeking. The truth is that, as a rule, 

 the pure biologist is engaged in work for the love of it, 

 and nothing is further from his thoughts than the 

 "practical" bearings or remote implications of what 

 he may discover. Indeed, many of his most hotly 

 pursued problems seem utterly divorced from what an 

 outsider would call practical bearings, though, to be 

 sure, one can never tell just what any new path may 

 lead to. Such, for example, is the problem which, 

 next to questions of cell activities, comes in for per- 

 haps as large a share of attention nowadays as any 

 other one biological topic namely, the question as to 

 just which of the various orders of invertebrate creat- 

 ures is the type from which vertebrates were evolved 

 in the past ages in other words, what invertebrate 

 creature was the direct ancestor of the vertebrates, in- 

 cluding man. Clearly it can be of very little practical 

 importance to man of to-day as to just who was his 

 ancestor of several million years ago. But just as 

 clearly the question has interest, and even the layman 

 can understand something of the enthusiasm with 

 which the specialist attacks it. 



As yet, it must be admitted, the question is not de- 

 cisively answered, several rival theories contending 

 for supremacy in the case. One of the most important 

 of these theories had its origin at the Naples labora- 

 tory; indeed, Dr. Dohrn himself is its author. This is 

 the view that the type of the invertebrate ancestor is 

 the annelid a form whose most familiar representa- 

 tive is the earth-worm. The many arguments for and 

 against accepting the credentials of this unaristocratic 

 ancestor cannot be dwelt upon here. But it may be 



