444 GLOSS. I A' y 



of the secondary spermatocytes, giving rise, according to Platner. to the mid- 

 dle-piece and tlie tail-envelope of tlie spermatozoon. Equivalent to tlie Neben- 

 kern of La \"alette St. George. (PLATNiiK, 1889.) 



Nebenkern (Paranucleus), a name originally applied by Butschli (1871) to an 

 extranuclear body in the spermatid : afterwards shown by La Valette St. George 

 and Platner to arise from the spindle-fibres of the secondary spermatocvte. 

 Since applied to many forms of cytoplasmic bodies (yolk-nucleus, etc) of the 

 most diverse nature. 



Nuclear plate, i. The equatorial plate. (Strasburger, 1875.) 2. The parti- 

 tion-wall which sometimes divides the nucleus in amitosis. 



Nuclein. the chemical basis of chromatin ; a compound of nucleinic acid and albumin 

 or albumin radicles. (Mif.scher, 1871.) 



Nucleinic or nucleic acid, a complex organic acid, rich in phosphorus, and an 

 essential constituent of chromatin. 



Nucleo-albumin. a nuclein having a relatively high percentage of albumin, Dis- 

 tinguished trum nucleo-proteids by containing paranucleinic acid which yields no 

 xanthin-l)odies. 



[Nucleochyle'ma] (^vAds. juice), the ground-substance of the nucleus as opposed 

 to that of the cytoplasm. (Strasblrger. 1882.) 



Nucleohy'aloplasma (see Hyaloplasm), the achromatic substance (hnin) in which 

 the chromatin-granules are suspended. (Strasburger, 1882.) 



Nucleomi'crosomes (see Microsome), the nuclear (chromatin) granules as 

 opposed to those of the cytoplasm. (Strasburger, 1882.) 



Nucleoplasm, i. The reticular substance of the (egg-) nucleus. (\^AN' Bene- 

 DEN, 1875.) 2. The substance of the nucleus as opposed to that of the cell- 

 body or cytoplasm. (Strasburger, 1882.) 



Nucleo-pro'teid, a nuclein having a relatively high percentage of albumin. May 

 be split into albumin and true nucleinic acid, the latter yielding xanthin-bodies. 



CEde'matin (oiSr^/xa. a swelling), the granules or microsomes of the nuclear ground- 

 substance. (Reixke, 1893.) 



Oocyte (Ovocyte) (wov. egg; ki^os, hollow (a cell)), the ultimate ovarian egg 

 before formation of the polar bodies. The primary oocyte divides to form the 

 first polar body and the secondary oocyte. The latter divides to form the second 

 polar body and the mature egg. (Boveri. 1891.) 



Oogenesis. Ovogenesis (wov, egg ; ycVecrts, origin), the genesis of the egg after its 

 origin by division from the mother-cell. Often used more specifically to denote 

 the process of reduction in the female. 



Oogonium, Ovogonium (woV, egg ; yovn], generation), i . The primordial mother- 

 cell from which arises the egg and its follicle. (Pfluger.) 2. The descend- 

 ants of the primordial germ-cell which ultimately give rise to the oocytes or 

 ovarian eggs. (BovERl, 1891.) 



Ookine'sis (woV, egg; KU'r;(ns, movement), the mitotic phenomena of the egg dur- 

 ing maturation and fertilization. (Whitman, 1887.) 



O'vocentre. the egg-centrosome during fertilization. (FoL, 1891.) 



Oxychro'matin (oiv<;. acid ; see Chromatin), that portion of the nuclear substance 

 stained by acid tar-colours. Equivalent to "linin"' in the usual sense. 

 (Heidenhaix, 1894.) 



Pangen'esis (ttus (Trar-), all : yeVecris, production), the theory of gemmules, accord- 

 ing to which hereditary traits are carried by invisible germs thrown off by the 

 individual cells of the body. (Darwix. 1868.) 



Pangens (ttcis (Traj/-). all : -yevTys, producing), the hypothetical ultimate supra-molec- 

 ular units of the idioplasm, and of the cell generally. Equivalent to gemmules, 

 micellie, idioblasts, biophores, etc. (De Vries, 1889.) 



