THE PINEAL BODY 159 



vessels, 4) certain cells called muscle or myoid cells, 5) lympho- 

 cytes, and 6) lymphoid reticulum. 



Hollard 188 in 1837 regarded the epiphysis as a glandular struc- 

 ture with nerve fibers in its peduncle only. Valentin 403 in 1843 

 believed that the pineal body possessed a parenchyma which 

 was something entirely different from the gray matter of the 

 brain. He observed certain 'nuclear formations ' which had a 

 striking resemblance to the tissue of the pituitary gland. Kolli- 

 ker 210 in 1850 described the epiphysis in mammals as consisting 

 of small, round cells, multipolar nerve cells and compact bundles 

 of nerve fibers. But it is to Faivre 114 in 1855 that we are 

 indebted for the first extensive study in the comparative his- 

 tology of the epiphysis. Faivre investigated microscopically 

 the pineal body of man, horse, guinea-pig, dog, ox, rabbit, and 

 pig. He recognized three elements in the human pineal body, 

 i.e., 1) a fibro vascular envelope, 2) a globular parenchyma, and 

 3) acervulus cerebri. Faivre's observation was in accord with 

 Valentin's, 403 that the pineal body differs essentially from the 

 brain. He concludes that the parenchyma is made up largely 

 of those globules which were nuclei of large elliptical cells in the 

 organ. He seems to have been the first to recognize that these 

 cells contained granules and also that the parenchymal cells 

 were smaller in the child than in the adult. Clarke 69 in 1860 

 found nerve fibers, nuclei and brain sand, but no nerve cells. 

 These elements were arranged in a reticular structure which 

 resembled the olfactory mucous membrane. Luys 253 in 1865 

 considered the organ as a structure composed of nerve cells 

 and fibers, in general, analogous to the mammillary bodies. 

 Leydig 232 in 1868 states that the pineal body in the mouse 

 resembles the pituitary gland in reptiles with certain small 

 differences. Frey ('67) 131 observed in adults multipolar gan- 

 glionic cells, rounded cells without prolongations and isolated 

 nerve tubes. Meynert (77)' 271 asserts that the parallelism 

 between the pituitary body and the epiphysis is a mistaken 

 idea. The pineal body should be considered a ganglionic deriva- 

 tive of the tegmentum. It contains two types of cells, one 

 having a diameter of 15 micromillimeters, the others 6 micro- 



