142 
Parasitic Worms 
There are in this way several different lines along which progress 
has been made. It is in many cases not a little difficult to estimate the 
relative importance of these advances, and it is a common experience 
that discoveries which appear, at first, to be of only academic interest 
occasionally prove of the greatest economic value. In consideration of 
the meeting at which this paper is being read, chief attention must 
naturally be paid to those features which are essentially of zoological 
interest and importance, but some space will also be devoted to their 
economic bearing. It is impossible in a short review, such as this, to 
deal adequately with all the work on the subject, so that, for the most 
part, only the work of the best known authorities will be considered. 
It is frequently a matter of difficulty to determine exactly what 
period of time is covered by the term recent. With our present rate of 
advance, ideas and views change with such remarkable rapidity that 
any one discovery, no matter of what importance, does not long remain 
a novelty, and it is generally the case that those of second rate value 
remain entirely unknown except to a few for whom they possess an 
especial interest. There is the further consideration, however, that in 
the course of time the matters of fundamental importance become 
common knowledge and, I venture to think that, under ordinary 
circumstances, a period of five or six years will elapse before this is the 
case. I have accordingly chosen this as the period with which to 
deal. 
It may be well, first of all, to consider the men who have been chiefly 
engaged in carrying out the work. Foremost amongst these must be 
mentioned the names of Looss, Fuhrmann, and Odhner, who have been 
mainly responsible for the great advances made in our knowledge of the 
flat-worms. Looss has also devoted considerable attention to the 
round-worms, which have received further treatment at the hands of 
Railliet and Henry. Amongst others whose work may be specially 
mentioned are Yon Linstow, who has devoted himself to helminthological 
research for the past fifty years, Stiles, Ransom, Ward and Linton, the 
foremost exponents of the American School, Ltihe in Germany and 
Goldschmidt, whose researches have been chiefly histological. In 
addition reference must be made to the excellent work of Porta and 
of Monticelli in Italy, of Weinberg in France and of Leiper, Shipley 
and Miss Lebour in this country. Even this long list, however, does 
not by any means exhaust the number of those who have specially 
interested themselves in the subject and have done outstanding work 
in it. 
