340 GLOSSARY 



Par'aplasni {Trapd, beside; TrAacr/xa, something formed), the less active portion of 

 the cell-substance. Originally applied by Kupffer to the cortical region of the 

 cell (exoplasm), hut now often applied to the ground-substance. (Kupffer, 



I875-) 



Per'iplast (TrepL around ; TrAacrros, form), a term somewhat vaguely applied to the 

 attraction-sphere. The term daughter-periplast is applied to the centrosome. 

 (\'FjnovsKV, 1888.) 



Plas'mosome (TrXdcrfxa, something formed (/.c. protoplasmic) ; crw/xa. body), the 

 true nucleolus, distinguished by its affinity for acid anilines and other •' plasma- 

 stains."' (Ogata, 1883.) 



Pla'sonie (TrAacr/xa, a thing formed; croj/xa. body), the ultimate supra-molecular 

 vital unit. See Biophore. Pangea. (Wiesner, 1890.) 



Plas'tid (TrAacTTos, form), i. A cell, whether nucleated or non-nucleated. (Hackel, 

 1866.) 2. A general term applied to permanent cell-organs (chloroplasts, etc.) 

 other than the nucleus and centrosome. (Schimper. 1883.) 



Plas'tidule. the ultimate supra-molecular vital unit. (Elssberg, 1874; Hackel, 

 1876.) 



Plas'tin, a term of vague meaning applied to a substance related to the nucleo- 

 proteids and nucleo-albumins constituting the linin-netwoik (Zacharias) and the 

 cytoreticulum (Carnoy). (Reinke and Rodewald, 1881.) 



Pluriva'lent {plus, more ; 7'alere. to be worth), applied to chromatin-rods that 

 have the value of more than one chromosome sensn strictii. (Hacker. 1892.) 



Polar bodies (Polar globules), two minute cells segmented off from the ovum 

 before union of the germ-nuclei. (Disc, by Carus, 1824; so named by Roiiix. 

 1862.) 



Polar corpuscle, the centrosome. (Va\ Bexeden. 1876.) 



Polar rays (Polradien). a term sometimes applied to all of the astral ravs as 

 opposed to the spindle-fibres, sometimes to the group of astral ravs opposite to 

 the spindle-fibres. 



Pole-plates (End-plates), the achromatic spheres or masses at the poles of the 

 spindle in the mitosis of Protozoa, probably representing the attraction-spheres. 

 (R. Hertwig. 1S77.) 



Polyspermy, the entrance into the ovum of more than one spermatozoon. 



Prochro 'matin (see Chromatin), the substance of true nucleoli, or plasmosomes. 

 Equivalent to paranuclein of O. Hertwig. (Pfitzner, 1883.) 



Pronuclei, the germ-nuclei during fertilization; /.t'.. the egg-nucleus (female pro- 

 nucleus) after formation of the polar bodies, and the sperm-nucleus (male pro- 

 nucleus) after entrance of the spermatozoon into the egg. ( Vax Bexeden, 

 1875.) 



[Prothy'alosome] (see Hyalosome). an area in tlie germinal vesicle {oi Ascan's) 

 by which the germinal spot is surrounded, and which is concerned in formation 

 of the first polar body. (Van Bexeden, 1S83.) 



Pro'toblast (Trpwro?. first : ^Aaoros, a germ), a naked cell, devoid of a membrane. 



(KOLLIKER.) 



Pro'toplasm (TrpoiTos. first ; TrAacr/xa. a thing formed or moulded), i. The living 

 substance of the cell, comprising cytoplasm and karyoplasm. (Purkyxe. 1840; 

 H. VON MoHL. 1846.) 2. The cytoplasm as opposed to the karyoplasm. 



Pro'toplast (TrpwTo?. first; TrAaord?. formed), i. The protoplasmic body of the 

 cell, including nucleus and cytoplasm, regarded as a unit. Nearly equi\-alent to 

 the energid of Sachs. (Han.steix. 1880.) 2. Used by some authors synony- 

 mous! v with plastid 



[Pseudochro'matin] (see Chromatin), the same as prochromatin. (Pfitz.ner, 

 1886.) 



