293 



The Sexual Conditions of Myzostoma glabrum 

 (F. S. Leuckart). 



By 

 J. Beard, 



D.Sc, University Lecturer in Comparative Embryology, Edinburgh. 



With Piate 10. 



Myzostoma glahrum^ a common parasite of Comatula in the Bay 

 of Naples, presents the peculiarity of hermaphroditisni associated 

 with the existence of »complemental« or dwarf males. In my originai 

 account (1) of these latter it was conchided \ that they were to be 

 looked upon as remnants of a forraer primitive dioccious state, and 

 that hermaphroditism in this, as in mauy other cases, was a secondary 

 condition, induced,, perhaps, by the parasitic mode of life. 



Nansen, in a valuable work (0) on the genus, regarded the 

 matter in a very diiferent light; in his opinion the so-called dwarf- 

 males had sprung from or were merely young protandrous herma- 

 phrodites. 



The results of investigations, undertaken to test the validity of 

 Nansen's contentions, are given below. They were primarily not 

 meant for publication'-^, but only for the satisfaction of personal 

 curiosity. As, however, Nansen's views bave found acceptance in 

 such standard works as Lang's Vergleichende Anatomie and Kor- 

 SCHELT and Heider's Entwicklungsgeschichte, the matter cannot 

 well be left unchallenged, seeing that Ican find no evidence to support 

 Nansen's suppositions, but much that strengthens my standpoint. 



It may be well to recali a few of the facts as to the occurrence 

 of M. glahrum. 



1 No. 1 of the appended list of memoirs. 



2 The first portion of this paper was originally written in 1890. Since 

 then the material has twice undergone revision. 



