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GLOSSARY 



AMPLEXUS - the sexual embrace ol' lemale by 

 the male amphibian. This may or may 

 not occur at the time of oviposition. 



AMPHOTEROKY - production of both sexes in 

 a single parthenogenetic brood. 



ANALOGOUS - structures said to have the same 

 function but different embryological and/or 

 evolutionary origin. Opposed to honnologous. 



ANDROGAMONES - the anti-fertilizins of Lillie, 

 so named by Hartmann. An acidic protein 

 of low molecular weight. 



ANDROGENESIS - development of the egg with 

 paternal (sperm) chromosonnes only, ac- 

 complished by removing the egg nucleus 

 after activation by the spermatozoon but 

 before syngamy (Wilson, 1925). May also 

 be accomplished by irradiation damage of 

 egg nucleus. 



ANDRO-MEROGONES - egg fragments develop- 

 ing with the sperm nucleus only, achieved 

 either through surgical rennoval of the egg 

 nucleus and some cytoplasm; by constrict- 

 ing the pro-nuclei apart prior to syngamy; 

 or by centrifuging the pro-nuclei apart. 



ANEUPLOIDY - deviation from normal diploidy 

 but involving partial sets of chromosonnes 

 (Tachkohn, 1922). 



ANEUPLOIDY, MULTIFORM - complex chrom- 

 osomal mosaics, possibly the result of 

 multipolar mitoses (Book, 1944). 



ANEUROGENIC - used in relation to organs de- 

 veloped without proper components of the 

 central nervous system (e. g. , limb buds 

 in embryos without spinal cords). 



ANENTERION - formation and constriction of 

 archenteron by evagination instead of in- 

 vagination, following the application of heat 

 (Driesch, 1895). 



ANGENESIS - regeneration of tissues. 



ANLAGE - a rudiment; a group of cells which 

 indicate a prospective development into a 

 part or organ. Syn. , ebauche' or primor- 

 dium. 



ANIMALIZATION - changing by physical or 

 chemical means the presumptive fate of 

 embryonic areas which normally would have 

 become endodermal. Syn. , ectodermiza- 

 tion, or animalisierung of Lindahl. 



ANORMOGENESE - a course of development 



which deviates in a typical manner fronn the 

 normal (Lehmann). 



ANTERIOR - toward the head; head end. Syn. , 

 cephalic, cranial, rostral. 



APROSOMUS - featureless face due to the arrest 

 of developnnent, the skin covering normal 

 but lacking in eyes, nose, and mouth. 



ARCHENCEPHALON - anterior portion of the 

 brain which gives rise to the telencephalon 

 and the diencephalon; pre-chordal brain. 



ARCHIPLASM - specific material which gives 

 rise to the asters and spindle (Boveri). 



AREA - a morphogenetic cell group represent- 

 ing one of the constituent regions of a fate- 

 map, generally of a blastula stage or later. 



AKEAL - first an invisible, then a sharply dif- 

 ferentiated region of the blastema, out of 

 which develops a primitive organ; the organ 

 arising from the blastema through segrega- 

 tion, (organogenetisches of Lehmann). 



AREA OPACA - the marginal ring or extra- 

 embryonic blastoderm of the chick embryo 

 around the area pellucida, opaque because 

 of direct contact with the underlying yolk. 



AREA PELLUCIDA - the central portion of the 

 chick blastoderm from which the embryo 

 is developed, pellucid because it is lifted 

 off of the underlying yolk, providing a space 

 beneath the blastoderm through which light 

 can be transmitted. 



AREA VASCULOSA - the portion of the area 



opaca of the chick blastodernn in which the 

 extra-embryonic blood vessels will develop. 



AREA VITELLINA - the portion of the area 



opaca of the chick blastoderm peripheral to 

 the area vasculosa. 



ARRHENOKARYOTIC - refers to a blastomere 

 of the normally fertilized egg where there 

 has been a separation of the nuclear com- 

 ponents; or in cases of dispermy, where 

 the haploid chromosomes from the single 

 sperm are isolated in the blastomere. 



ARRHENOTOKY - parthenogenetic production 

 of males, exclusively. 



ASSIMILATION - process of determinative in- 

 corporation of a foreign blastema into the 

 functional status of the host blastema, 



ASTER - the "star-shaped structure" surround- 

 ing the centrosome (Fol, 1877); lines rad- 

 iating in all directions from the centrosome 

 during mitosis. 



ASTOMUS - complete lack or atresia of the 

 mouth. 



ASYNTAXIA DORSALIS - failure of the neural 

 tube to close. 



ATELIOTIC - arrested development of the skel- 

 eton due to non-union of the epiphyses, 

 characteristic of some dwarfs. 



ATOKUS - without offspring. 



ATTRACTION, NON-SPECIFIC - attraction of 

 nerve fibers toward any structure in the 

 vicinity, (e. g. , graft rudiments of chick 

 embryos such as brain tissue, if placed on 

 the chorio-allantois, will often send out 

 nerve fibers toward the nearby muscle seg- 

 ments, a situation that would not occur un- 

 der normal conditions). 



AUFLAGERUNG - the placing of competent or 

 responsive ectoderm on a dead inductor in 

 order to test the inductive power of the 

 latter. 



AUTOGAMY - self-fertilization. 



AUTOPARTHENOGENESIS - parthenogenetic 



stimulation of eggs to develop by materials 

 from other eggs. 



AUXESIS - growth by cell expansion but without 

 cell division. 



AXIS - central or median line. The egg axis 

 takes into account the concentration of 



