Caponise, Caponising — 23 — Certation 



Centriole. — A central deeply staining particle in the centro- 

 some. This in some organisms replaces the centrosome. 



Centrodesmose, Centrodesmus, Centrodesm. — The deli- 

 cate fibril (or fibrils) joining the two centrosomes at mitosis. 



Centrogene. — The attachment particle as distinct from the 

 attachment region or centromere. 



Centrolecithal. — Of ova: having the yolk centrally placed. 



Centromere. — Spindle attachment; insertion region; kine- 

 tochore; a non-staining, localized region in each chromosome 

 to which the spindle 'fibre' appears to be attached at meta- 

 phase. The centromere remains single for some time after 

 the rest of the chromosome has divided, and, at anaphase, 

 starts to move towards the pole before the rest of the chroma- 

 tid. 



Centronucleus. — A nucleus that contains a central body or 

 which itself plays the part of a division centre (Boveri: Wil- 

 son). 



Centroplasm. — The protoplasm in the centrosphere zone dur- 

 ing cell division. 



Centroplast. — An extranuclear spherical body forming divi- 

 sion centre of mitosis in certain lower organisms (Henderson). 



Centrosome. — The self-propagating centre of activity in cell 

 division in most animal cells and in the Thallophyta. It con- 

 sists of an attraction sphere which may contain a small highly 

 staining granule (centriole) and it appears to determine the 

 orientation of the spindle. 



Centrosphere. — The less deeply staining substance which 

 surrounds the centriole and makes up the body of the centro- 

 some. In organisms lacking a centriole the centrosphere is 

 synonymous with the centrosome. 



Centrosphere, Giant. — According to Lewis (1920) this con- 

 sists of a centriole contained within a medullary zone which 

 stains deeper than an external cortical zone and from which it 

 is separated by a thin membrane (Ludford, 1945). 



Centrotheca. — Idiozome, q.v. 



Centrum. — Central body, q.v. 



Cephalization. — Tendency in ascending evolution to spe- 

 cialization of anterior end of organisms (Beadnell). 



Cephalobrachial. — Of a chromosome: bearing a terminal, 

 knob-like extension. 



Certation. — Competition as between pollen grains of dififer- 

 ent genotype, in the rapidity with which they can grow down 

 the style; agonisis. 



