THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[FIFTH SERIES.] 

 No. 113. MAY 1887. 



XLI. — Parasitic Castration, and its hijlueyice upon the Exter- 

 nal Characters of the Male Sex, in the Decapod Crustacea, 

 By Prof. A. Giakd*. 



" Whatever may be said concerning the advantages to the 

 experimenter of having no preconceived idea, it is proved 

 by innumerable examples that one often misses those pheno- 

 mena which one did not expect to meet with, and tiiat obser- 

 vation is much more intense and much more fruitful when the 

 investigator knows beforehand what he ought to find, and 

 strives pertinaciously to find it, notwithstanding want of success 

 at the outset " f- 



In these words, when commencing his course last year, 

 one of the masters of biology in France expressed himself, 

 and there never has been a statement more useful to repeat. 

 To be convinced of this we have only to run through the 

 memoirs produced for some time past in most of our zoo- 

 logical laboratories. The triumph of the school of Cuvier 

 is now-a-days complete ; the intolerant dogmatism and the 

 exclusively empirical tendencies of those who occiipy the 

 chairs of authority no longer permit any general views. Im- 



* Translated by W. S. Dallas, F.L.S., from a separate copy, fiiruished 

 by the author, of the paper in the ' liulletin Scientitique du Nord,' 

 ser. 2, annee x., 1887. 



t Marev, " Les liOis de la Mecanique eu Biologie,"' ' Kevue Rose,' 

 .3nl July, "1880, p. 3. 



Ann & M<i(j. N. Hist. iScr. 5. I o/. xix. 23 



