280 Platybdella Anarrhichae 
act of secretion, and particularly in specimens caught in winter or in 
the early part of the year, appear on this account so numerous as to 
give to the cytoplasm a uniformly dotted appearance. The secretion 
which is given off nils ultimately a large part of the cell, and seems 
within the cell as well as in the greater part of the efferent duct not 
completely homogeneous; near to the commencement of the duct it 
shows itself granular. The nuclei, according to Johansson, are 
ultimately destroyed whereby the secretory power of the gland comes 
to an end. He bases this conclusion on the fact that old individuals 
possess numbers of such exhausted cells among the functional ones. 
Such enucleated cells were not found in any of the leeches sectioned 
Fig. 4. Platybdella anarrhichae. Transverse section of the leech in the anterior portion 
of the abdomen. St. stomach ; t. testes; c.g.d.b. cocoon gland duct bundles beginning 
to scatter; d.s. dorsal sinus; v.s. ventral sinus; l.s. lateral sinus; v.b.v. ventral 
blood vessel; n.g. ganglion on ventral nerve cord; v.e. vas efferens; x. body'wall. 
The shaded part includes the whole of the layers shown in enlarged detail in Fig. 2. 
by me, but I understand that Dr Henry has found them in his specimens. 
The cells exhibit the curious phenomenon of unicellular glands. The 
efferent ducts of the cocoon gland cells, which naturally increase in 
length according to the distance of the gland-cell from the clitellum, are 
wide just at the border of the cell from which they spring (Fig. 3), 
but quickly narrow to fine tubes which run forward without winding 
until they come to the clitellum (Fig. 4). Here they bend more or less 
at an angle from their original direction, perform several windings, and 
open thereupon on the whole surface of this region, except a little circle 
surrounding the genital openings. The apertures of the ducts are 
extremely fine. The efferent ducts do not, however, run forward 
