164 bulletin: museum of comparative zoology. 



These glandular cells are cro^vded with a mass of spherical vacuoles, 

 which are smaller in the attached end of the cell than in its free end 

 (Figure 4), and sometimes are not found at all in its basal part (Figure 

 5). The cytoplasm also contains granules of various sizes and shapes, 

 which differ widely in refractive powers. These are found throughout 

 the cell, often in compact opaque masses. Such masses are also common 

 in the globules (Figure 4). 



In sections prepared by certain methods, namely, in material fixed in 

 saturated aqueous-corrosive sublimate, or in vom Rath's platinic-aceto- 

 osmic mixture, acicular crystals are found in many cells, though not 

 in all. Such crystals are not found in material treated with Perenyi's 

 fluid or with Flemming's weaker mixture, nor in any sections which 

 have been decolorized with alcohol acidulated with 1% HCl. These 

 crystals are all fine and needle-like, but diff'er in length (Fig. 5, cry., and 

 Fig. 6). It is noticeable that they are confined to the cells of the end- 

 sac, none being found either in the lumen of the endsac or in the cells or 

 lumina of labyrinth or vesicle. 



Szigethy ('85, p. 109) found in the gland of Astacus crystals which he 

 regarded as uric acid. I have not seen his figures in the original paper, 

 and so cannot compare them with those I have described. In the present 

 case, I think it probable that the crystals are ai'tifacts ; at any rate, 

 more detailed in\^stigation is necessary before they can be considered of 

 physiological importance. I have simply made a record of the condition 

 noticed. 



The nuclei of the cells of the endsac are oval and usually situated in 

 the basal half of the cell ; but in some cases they are crowded toward 

 the free end (Figure 4). The cells rest upon a membrane {pih. ba.^ 

 Fi^s. 4 and 5) of appreciable thickness, but without nuclei. 



'I'here is but one region of communication between endsac and labyrinth. 

 This is in the main axis of the gland immediately posterior to the bottom 

 of tlie liihis. The section from which Figure 2 is drawn passes through 

 this region. The communication is between the central lumen of the 

 endsac and the lateral anterior lobe of the labyrinth. The median an- 

 terior lobe has no direct communication with the endsac, but it will be 

 reineml)i'red that it is from the median anterior lobe that the white lobe 

 — wliich is the direct passage to the exterior — arises (p. 159). There- 

 fore tlie products of the endsac must pass througli the lateral-anterior, 

 the median-anterior, and the white lobes in the order named before reach- 

 ing the duct to the exterior. Tlie communication between the en^lsac 

 and the lateral-anterior lube is about 0.4 millimetre in diameter, and 



