GLOSSARY 



The following list contains the explanations of a number of 

 biological technical terms used in this book. 



Amoeboid movement: movement by means of pseudopodia ('false 



feet', protoplasmic processes), similar to that of an Amoeba. 

 Amphiaster: double star, consisting of two asters connected by a 



mitotic spindle. Cf. monaster. 

 Amphimtvis: fusion of two gametes (in particular: fusion of their 



nuclei), formed by two different individuaJs. 

 Androgamone: fertilisation substance produced by the male germ 



cells. Cf. gamone, gynogamone. 

 Animal pole: pole of the egg at which the polar bodies are formed. 



Opp.: vegetative pole. 

 Assimilative induction: influence which causes other cells to develop 



in the same way as those of the inductor. 

 Aster: star-shaped structure in the cytoplasm, formed by local 



gelation. 

 Atrophy: reduction in size and functional activity. Cf. hypertrophy. 

 Autonomisation: process leading to independence of the parts of 



a whole. 

 Bilateral symmetry: case of symmetry in which there is only one 



symmetry plane, i.e. in which the body can be divided into 



symmetrical halves in only one way. 

 Blastema: organ primordium consisting of undifferentiated cells. 

 Blastomere: cell formed by the cleavage of the egg. 

 Blastula: vesicular stage of cleavage, with an internal cavity. 

 Caudal: pertaining to or directed towards the tail. Opp.: cranial, 



rostral. 

 Centrifuge: rapidly rotating apparatus for subjecting bodies to 



strong centrifugal forces. 

 Centrosome: corpuscle forming the centre of an aster, or a pole of 



a mitotic spindle. 

 Chemodifferentiation: division of a whole into parts differing in 



their (physical and) chemical properties. 

 Chimaera: organism consisting of tissues belonging to different 



species. 

 Chromatin: substance with a high affinity for stains, localised in 



the nucleus. 

 Chromidium: cytoplasmic granule with high affinity for stains. 

 Chromosome: corpuscle containing the chromatin during nuclear 



division. 



