Contributions to the Anatomy and Histology of Thalassema neptuni Gaertner. 541 



condition. The frequent existence of intercellular spaces due to 

 imperfect preservation of the epidermis makes the interpretation of 

 these clear cells still more difficult. 



3) The great unicellular glands, Figs. 2, 5 and 6, are situated 

 on the papillae, on the surfaces of which they open in irregular groups, 

 piercing the cuticle as already described (Figs. 2, 2 a and 4). They 

 are pear-shaped or flask -shaped with an attenuated neck and a 

 swollen body which projects into the underlying cutis. In the body 

 wall they often extend as far as the inner limit of the cutis, while in the 

 proboscis they are actually embedded in the musculature. These gland 

 cells form the greater part of the substance of the fleshy papillae of 

 the skin. On the proboscis they present in general the same structure 

 as on the body, but are smaller and are not collected into special 

 groups. The nuclei of these glands stain more deeply than those of 

 the epidermal cells; they are more regular in form, being generally 

 spherical or slightly ovate and more highly opaque; they possess a single 

 dark refractive spot near their centres; their normal position is in 

 the basal ends of the cells. I can nowhere detect the presence of 

 more than one nucleus to a gland cell , although the fact that the 

 more elongate nuclei of the epidermis and connective tissue are often 

 closely apposed to their walls, owing to the compressed condition 

 of the surrounding tissues, sometimes gives one at first the im- 

 pression of such a condition. The nuclei are represented in Fig. 2 

 gl.n. The contents of these glands stain very difl'erently in different 

 cells and in different parts of the same cell, no doubt owing to 

 differences in the degree of elaboration of the secretion. They stain 

 deeply with most aniline dyes and with thyonin give the red 

 colour characteristic of mucin. In preparations consecutively handled 

 with osmic acid and pyroligueous acid we get a more or less clear 

 reticular matrix containing a varying number of deep black granules 

 (Fig. 2 gfr, Fig. 5). There is generally more or less undifferentiated 

 protoplasm around the nucleus, which in osmium-pyroligneous pre- 

 parations that have previously been stained in borax carmine retains 

 its red colour. 



4) The sense organs. These organs are chiefly to be reco- 

 gnised on the proboscis, although I have seen apparently similar 

 structures more rarely on the papillae, which however, owing to the 

 crowding of the gland cells, were less easy to interpret. On the pro- 

 boscis they lie in considerable numbers along the lateral margins, 

 more particularly at the distal end. They consist of groups of elongated 



