LABUAL GLANDS OF SIMOCBPHALUS 217 



times, that of the nucleus of a nerve- or muscle-cell. The 

 chromatin in these nuclei is distributed fairly evenly in small 

 clumps (PI. 10, fig. 9), and there is a conspicuous oval nucleolus 

 Avhich stains red with Mallory's stain. The cell outhnes are 

 not distinct, hut where one would expect the cell boundaries 

 to be there are accumulations of large clear vacuoles (PI. 10, 

 fig. 9), undoubtedly the secretory product of these cells. In 

 the peripheral cells of this group the cytoplasm is not very 

 vacuolated, the vacuoles being very markedly intercellular ; 

 but more centrally and towards the anterior end the whole of 

 the cytoplasm of the cells is full of small vacuoles while the 

 larger vacuoles lie in between the cells. In this region the 

 proximal group is seen to be attached to the distal group of 

 gland-cells (Pis. 9 and 10, figs. 3 and 9). 



The proximal group is supplied by a small branch of the nerve 

 to antenna 1 which comes off very near to the brain. There 

 is no elTerent duct from the proximal group as described by 

 Claus. 



The Distal Group. — The distal glands (Text-fig. 1) on 

 each side consist of five cells, four gland-cells and a duct-cell. 

 The gland-cells are arranged in two pairs situated anteriorly 

 and posteriorly, connected with each other— the hinder pair 

 embracing the duct-cell. 



The anterior pair of cells are in direct connexion with the 

 posterior side of the nerve to the first antenna at a point a little 

 further from the brain than the branch to the proximal group 

 (Pis. 9 and 10, figs. 2 and 13), and there is a conspicuous group 

 of nerve-cells in the nerve in this region (PI. 9, fig. 2). Laterally, 

 as stated above, these cells are connected with the proximal 

 group, and at this point the vacuolated cytoplasm of the 

 proximal gland-cells is seen to be continuous with that of the 

 distal gland-cells, the vacvioles passing freely from one group 

 to the other (PL 10, fig. 9). The peripheral cytoplasm, except 

 at this point of juncture, is denser than that in the interior of 

 the cells, and is free from vacuoles of secretion (PI. 10, fig. 9). 

 There is no distinct division between these two cells, but in 

 between the two nuclei there is a confused mass of vacuoles. 



