Sl'UDIES ON THE ECTOPARASITIC TEEMATODES OF JAPAX. 41 



part of its interior was occupied by one or more clear vacuoles. The 

 nucleus, which enclosed a single nucleolus, sometimes occupied a 

 central position, but usually lay moi-e or less towards the pei-iphery of 

 the cell ; and in most cases was surrounded by a mass of granular cyto- 

 plasm, which was stained in haematoxylin more deeply than the nucleus 

 itself. From this central mass the cytoplasm radiated, in most cjises, 

 in the form of a few threads towards the cell-wall (PI. XXI, figs. 2 

 & 3). Each cell is prolonged at one of its corners into a long duct ; 

 and the ducts of a single group, after proceeding together for a short 

 distance towards the lateral border, are divided into two bundles, 

 which diverge from each other, and again unite just before opening 

 on the dorsal surface of the body, close to its lateral margin. 



From the above description, the glandular nature of these cells is, 

 I believe, beyond doubt ; and comparing them with the cells of the 

 submaxillary giands^^ of the mammalia, there is such a similarity 

 between the two that it is perhaps allowable to conclude that these 

 unicellular glands secrete mucin and help to attach the body of the 

 parasite more securely to its host. 



The opening of the gland above described is armed with a 

 chitinous piece, which is represented in surface view in fig. 3, PI. XX, 

 and in section in its natural position in fig. 3, PI. XXI for T. siniia- 

 tum, and in fig. 5, PI. XXV, for T. biparasiticiim. In T. rotundum 

 similar chitinous pieces (PI. XXIV, fig. 7) are arranged in transverse 

 rows along the lateral margin of the body just as in Tr. molm^^ ; a 

 single row consisting of four or five pieces in the middle portion of 

 the body, but of only one or two towards the ends. In this species, 



1). Landois.— Lehrbuoli der Physiologie des Menschen. 6. Aufl. p. 268-270. 



2). Parona e Perugia. — Ees ligusticae, VIII. Di alcuni trematodi eotoparassiti di peaci 

 marini. Xota preventiTa. Annali del Museo Civico di Storia \aturale di Geneva. Ser. 2, vol 

 VII. p. 741. 



