GLOSSARY 193 



Monospermy: fertilisation by a single sperm. Cf. dispermy, poly- 

 spermy. 



Morphallaxis : restitution by the transformation and shifting of 

 material, not by growth. Cf. reorganisation. 



Morphogenesis: the origin of form. 



Morphology: the science of form. 



Mutant: individual or race arising by mutation. 



Mutation: spontaneous change in an inheritable property. 



Neoblast: undifferentiated cell in the body of an adult animal, which 

 plays a role in regeneration. 



Neo-epigenesis: the hypothesis that the embryo develops from a 

 structureless egg. Cf. Neo-evolutio. 



Neo-evolutio : the hypothesis that the egg already contains an in- 

 visible spatial structure, from which the embryo will later 

 develop. Cf. Neo-epigenesis. 



Neural: pertaining to the nervous system. 



Neurula: developmental stage, subsequent to the gastrula stage, 

 in which the primordium of the central nervous system (the 

 neural plate) has developed from the ectoderm. 



Neurulation: the development of a neurula from a gastrula. 



Notochord: axial rod, in the body of Tunicates and Vertebrates. 



Nucleoplasm: non-chromatic content of the nucleus, nuclear sap. 



Omentum: a fold of the peritoneum. 



Omnipotent: capable of development into any organ or tissue. 



Oocyte: unripe egg, before the completion of the maturation 

 divisions. 



Oogonium: mother cell of the egg. 



Organisation: arrangement of the parts of a whole into an orderly 

 system of organs. 



Organisation centre: part of the germ, which plays a leading role in 

 the organisation of the embryo. 



Organiser: cell group which incites tissues to form an organised 

 system of organs. 



Organogenesis: the development of organs. 



Ovary: female reproductive gland. Cf. testis. 



Oxidase: enzyme promoting oxidation by oxygen. Cf. peroxidase. 



Parthenogenesis: reproduction by means of gametes which develop 

 without fertilisation. 



Patrocline: in which the paternal characteristics dominate over the 

 maternal ones. Opp.: matrocline. 



Pentaploid: containing five sets of chromosomes. Cf. diploid, haploid, 

 triploid. 



Peristome: mouth area. 



Perivitelline space: the interspace between the egg and the fer- 

 tilisation membrane. 



Peroxidase: enzyme which liberates oxygen from peroxides. Cf. 

 oxidase. 



Raven - Outline Physiology 13 



