334 Prof. A. Giard on Parasitic Castration 



which exist in a less degree in tlie female. It is reasonable 

 to suppose that the atrophy of tlie genital glands must have 

 an influence upon the development of these external organs. 

 Lastly, as it is very probable tliat Kathke did not undertake 

 a complete dissection of the infested prawns which he ex- 

 amined, and that he no doubt contented himself with a deter- 

 mination of the sexes by the most prominent external cha- 

 racters, there is room for an inquiry whether this determination 

 may not have been rendered erroneous by the influence of the 

 parasite itself, and whether Rathke did not regard as females 

 males in which the presence of the Bopyrus had hindered the 

 manifestation of the external sexual characters. 



This very interesting verification might be quickly made 

 in localities where Bopyrus is abundant. I may indicate 

 as a particularly favourable spot for this investigation the 

 little port of St. Vaast-la-Hougue. Some years ago (in 

 1875) 1 there found Bopyrus squillarum in great abundance. 

 Unfortunately at that time the question under discussion had 

 not yet arisen, and I paid no attention to the matter. 



Besides the preceding cases a single example of parasitic 

 castration is noted elsewhere among the Crustacea, namely 

 that of a Copepod, Cyclops tenuicomis^ infested by larvEe of 

 Distoma, and in consequence presenting embryonic characters 

 during its whole life *. 



IV. 



A case of parasitic castration absolutely comparable to that 

 which we have just studied in the Decapod Crustacea has been 

 indicated by Perez in the Hymenopterous insects of the genus 

 Andrena infested by Stylops f. The communication of the 

 learned professor of Bordeaux is most interesting, and does not 

 seem to have been sutficiently appreciated by Frencli and 

 foreign zoologists. Hence we think it will be serviceable to 

 reproduce here the summary of it, which was given in the 

 ' Revue Internationale des Sciences.' 



Having remarked that certain species of Andrena constantly 

 bear a parasite, and having closely examined these species, 

 Perez recognized that they are only abnormal forms of other 

 species ; and this led him to study the anatomical modifica- 

 tions which, in the bee, are correlative with the presence of a 

 parasite. 



* Herrick, " Heterogenetic Development iu Diaptomus" ' American 

 Naturalist,' vol. xviii. 



t Perez, " Des effets du parasitisme des Stylopes sur les Apiaires du 

 gem-e Andrena'' (Soc. des Sci. plijs. et Nat. de Bordeaux, 12tli June, 

 1879 ; ' Revue interuatiouale des Sciences,' tome iv. p. 281). 



