THE PINEAL BODY OF THE SHEEP 251 



week (2.5 cm.) when the pineal body is merely a shallow ependy- 

 mal pocket evaginated from the roof of the diencephalon, to the 

 third year when it shows numerous marks of degenerative changes. 

 Assuming, on gross anatomical and experimental basis, that the 

 pineal body of the sheep is a gland, and that it elaborates an inter- 

 nal secretion which exerts specific effects, (probably not indispen- 

 sable to the life or health of the animal), the primary object was 

 to discover signs of cytoplasmic activity at some period of its 

 development, expressed in granules, vacuoles, etc., indicating 

 secretory function. 



MATERIAL AND METHODS 



Through the kindness of Dr. Kingsbury, specimens of young 

 sheep embryos, including 2.5 cm. stages, were examined in the 

 embryological collection of Cornell University. My own material 

 includes glands from foetuses of the following lengths: 5, 10, 

 11 (ca. 1 month), 15, 17, and 21 (ca. 2^ months) cms.; also three 

 heads of foetuses of the last week of gestation (i.e., ca. 4f months). 

 All of this material was preserved in 10 per cent formaldehyde, 

 and stained in Delafield's or iron-haematoxylin with a variety of 

 counterstains. Besides this foetal material, my sections comprise 

 numerous glands of lambs (ca. 8 months) and adult sheep (up to 

 3 years). The latter material was fixed in a variety of fluidssuited 

 severally to a variety of stains, and sectioned either in paraffin 

 or celloidin. Among the various combinations employed, it 

 seems important to name the following: strong Flemming's 

 fluid (for lipoid granules, and cytoplasmic structure), Helly's 

 fluid (for phaeochrome granules), Miiller's and Ehlicki's fluids 

 (for the Weigert-Pal staining technic), Carnoy's fluid, picroacetic, 

 95 per cent alcohol, and 10 per cent formaldehyde (for general 

 cytoplasmic structure). Iron-haematoxylin was used as a neu- 

 roglia stain. For study of the connective tissue elements, Van 

 Gieson's, Mallory's, and Weigert's resorcin fuchsin stains were 

 employed. Non-medullated nerve-fibers were searched for in 

 fresh (from extirpated glands) tissue treated with the methylene 

 blue technic. Macerated material was also employed for various 

 purposes. 



