STUDIES OX THE ECTOPARASITIC TREMATODES OF JAPAN. XI 



nature. These ^'ie^Ys may be di\ided into two classes, viz., that which 

 reofards the investinsr membrane as a true cuticle, and tliat which 

 regards it as the transformed product of the oriirinally cellular 

 epidermis. Among the most recent writers on ectoparasitic Tre- 

 matodes, Brandes represents the first view and Braun the second.'^ 

 Accordino' to the former writer"-' the investino- membrane is to be 

 regarded as a true cuticle and as the secretion product of numerous 

 unicellular glands scattered in groups in the cortical portion of the 

 mesenchyma (Ectoparenchym), the presence of which he claims to have 

 demonstrated in all the forms studied by him f)r the ])urpose. In 

 opposition to this view, ]3raun^^ brings forward the fict that in Mono- 

 stomuni viutahilc there are disseminated in the investi nii* membrane 

 ("Hautschicht") numerous oval nuclei with sharp outline juid stain- 

 ing Aveakly with picro-carmin. In absence of nnv direct euibryolog- 

 ical proof it is of course useless to dogmatise on either side. But, even 

 laying aside the fact observed by Schwarze" that the investing 

 membrane of Ccrciiria is a transformed epidermis as not (piite conclu- 

 sive Avith respect to that of the adult worm, the positive facts''^ 

 at present known, when taken together seem to me to be strongly in 

 favour of the view upheld by Braun. For instance, the observa- 

 tion of Zeller*^^ on Pohjstomuuu tliat in it the epidermal cells are not 

 cast off but have their nuclei merely shrivelled up, strongly points to 



1). As stated in a previous note Monticelli is of the same opinion. 



2). Brandes — /. f. 



3). Brann— Ueber einige wenig bekannte resp. neue Treinatodea. Verliandl. d. deutsch, 

 zool. Gesellsch., 1S92. p. 51. 



4). Schwarze— Die postembryon. Entwiekl. d. Trematoden. Zeitsch. f. wiss. Zoolog., Bd. 

 42, 1886. p. 49. 



5). It is perhaps hardly necessary to remark here that the " matrix cells " o£ Wierzejski 

 are in reality the nuclei of the mesenchyma. Cf. Wierzejski in Zeitsch. f. wiss. Zoolog., Bd. 29, 

 1877. p. 552. 



G). Zeller— Weiterer Beitrag z. Kenntniss d. Polystomen. Zeitsch. f. wiss. Zoolog., Bd. 27 

 1876. p. 262. 



