THE PINEAL BODY 183 



4. Zalophus calif ornianus. In the sea-lion, although it is 

 difficult to discern the four types of cells already described with 

 clearness, as in the forms already noted, nevertheless, in certain 

 areas there appear many large cells with extensive nuclei which 

 stain deeply. Here and there scattered throughout the body 

 appear large cells of relatively the same size as those just men- 

 tioned, the nuclei of which, however, stain but faintly. Small 

 cells with deeply staining pycnotic nuclei are present in numbers 

 about equal to that of the first type while a small variety of 

 cell whose nucleus stains feebly is the least common variety 

 observed. The cells arrange themselves in cords or columns 

 which, upon transverse section, seem to be circular. These 

 cords apparently are much convoluted and not infrequently a 

 section of what appears to be the same cords is seen in transverse 

 as well as longitudinal outline. There is a rich connective tissue 

 network which appears to surround the cell cords. The pineal 

 body in Zalophus is highly vascular. No concretions were 

 observed (fig. 87). 



5. Lepus cuniculus. In the rabbit the pineal body is long and 

 cylindrical in form. In it may be recognized the four types of 

 cells already described, the predominant type being the large 

 cell with abundant granular cytoplasm and a large deeply stain- 

 ing nucleus. Dispersed among these cells are small cells of both 

 types and the large cells with faintly staining nuclei. The 

 general arrangement of the cells in this body is that of columns 

 or cords whose long axes are transverse to the axis of the pineal 

 gland itself. The columns of cells are separated by delicate 

 trabeculae of connective tissue in the meshes of which capillary 

 vessels make their way. Each of the cell cords varies in thick- 

 ness in different parts. They are seldom more than six to 

 eight cells deep, but in some places their transverse diameter 

 seems to be the thickness of two cells. The gland is very vas- 

 cular and no concretions are seen (fig. 88). 



6. Simia satyrus. In the orang, it is not difficult to recognize 

 the four types of cells already described in the other forms. 

 Perhaps the chief difference in the histology of the gland in 

 this animal is the great prominence which the large cells attain 



