162 FREDERICK TILNEY AND LUTHER F. WARREN 



separated by connective-tissue trabeculae. He also mentions 

 calcareous deposits in domestic animals. Mingazzini ('89) 276 

 believes the pineal elements resemble lymphatic corpuscles. 

 Soury ('99) 365 found a substance like adenoid tissue filling the 

 spaces of a fine network. Weigert ('95) 419 describes the pineal 

 body, especially its ventral portion, as composed of a thick 

 layer of neuroglia fibers of such a specific nature that the like of 

 it is not found elsewhere in the central nervous system. The 

 cells are very numerous and traversed by many fibers. Cajal 

 ('95) 53 found sympathetic fibers entering the pineal body with 

 the vessels. These fibers form a rich interstitial plexus. The 

 fibers surround but do not penetrate the cytoplasm of the 

 glandular cells. Galeotti ('96-'97) 14 makes the claim that 

 the pineal body is a secretory organ and believes there is evi- 

 dence of this in many vertebrates besides mammals. The pineal 

 cells elaborate a pigment in addition to their secretory product. 

 He recognized nerve cells which are in relation with the superior 

 and posterior commissures, ependymal cells constituting the 

 middle portion of the body, in relation with the pineal recess, 

 and epithelial cells which constitute the epiphyseal tube in some 

 animals and the epiphysis in mammals. Lord ('99) 249 described 

 the parenchyma of the human pineal body as formed of small 

 stellate cells resembling those of adenoid tissue together with 

 other paler cells of variable size. Nicolas ('00) 283B found striated 

 muscle cells in the distal portion of the pineal body in the ox and 

 calf. Dimitrova ('01), 92 a pupil of Nicolas', studied the pineal 

 body in mammals, young and old, including man, ox, calf, sheep, 

 horse, dog, and cat. She maintains that Nicolas' observations 

 were confirmed by her studies and that striped muscle cells do 

 occur in the pineal body of the ox and calf. In her opinion, 

 the essential constituent of the epiphysis in mammals is neuroglia 

 and she concludes that in addition to the essential neuroglial 

 nature of the pineal body there exists in the ox, calf, sheep, and 

 dog certain cavities which resemble thyroid vesicles or the 

 anterior pituitary lobe. In young cats some cells which are 

 independent of the neuroglia seem to resemble the elements 

 described by Cajal 54 and Retzius 331A as sympathetic' and may be 



