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GLOSSARY 



DOUBLE ASSURANCE - cases where induc- 

 tions usually occur but are not absolutely 

 necessary; two processes working together, 

 either one of which would be sufficient to 

 accomplish the end result. Ability to bring 

 about a morphogenetic process by means 

 other than the usual one, (e. g. , removal of 

 the eye cup in R. esculenta and the overly- 

 ing ectoderm will form a lens anyway, with- 

 out the nornnal inducing influences of the 

 eye cup). Term used by Rhumbler (1897) 

 in connection with cell division and by H. 

 Braus (1906) in development. Syn. , dop- 

 pelte sicherung. 



DUPLICITAS CRUCIATA - double monsters, 

 obtained by grafting or by inversion of the 

 2-cell amphibian embryo. 



DUPLICITAS INFERIOR - conjoined twins fused 

 anteriorly, having two rumps. Syn., dipygus. 



DYSMEROGENESIS - cleavage resulting in un- 

 like parts. 



DYSPLASTIC TREATMENT - introduction of a 

 transplant from organism of a different 

 phylum. (E. g. , frog to mammal or vice 

 versa. ) 



DYSTELEOLOGY - apparent lack of purpose in 

 organic processes or structures although 

 they may ultimately be shown to be teleo- 

 logical. 



ECDYSIS - process of moulting a cuticular layer, 

 shedding of epithelium by amphibia. 



ECHINOCHROME - red pigment of Echinoderm 



eggs which probably has respiratory function. 



ECTODERM - the outermost layer of a didermic 

 embryo (gastrula). Syn. , epiblast. 



ECTOPIC - out of its normal position, used in 

 connection with transplants. 



ECTOPLASM - external layer of protoplasm of 

 the (egg) cell, the layer immediately be- 

 neath the cell membrane. Seat of Lillie's 

 fertilizin and of all developmental processes, 

 according to Just. Syn. , egg cortex plasma- 

 lemma. 



EGG, ALECITHAL - eggs with little or no yolk. 



EGG, CLEIDOIC - egg which is covered by a 

 protective shell (e. g. , eggs of reptiles, 

 birds, and oviparous mammals). 



EGG, ECTOLECITHAL - egg having the forma- 

 tive protoplasm surrounded by yolk. 



EGG ENVELOPE - material enveloping the egg 

 but not necessarily a part of the egg, gen- 

 erally derived from the ovary (vitelline 

 membrane or chorion of fish) or from the 

 oviducts (jelly or albumen). 



EGG, GIANT - abnormal polyploid condition 

 where chromosome complexes are multi- 

 plied, resulting in giant cells and embryos. - 



EGG, HOMOLECITHAL - egg which has little 

 yolk scattered evenly throughout the cyto- 

 plasm(e,g., sea urchin, mammal). Syn., iso- 

 lecithal egg and absolete term, alecithal egg. 



EGG JELLY - the mucin covering deposited on 

 the amphibian egg as it pass.es through the 

 oviduct. 



EGG, MACROLECITHAL - egg with large 

 amount of yolk, generally telolecithal. 



EGG MEMBRANES - includes all egg coverings 

 such as vitelline membrane, chorion, and 

 the tertiary coverings from the oviduct. 



EGG, MICROLECITHAL - egg with small amount 

 of yolk. Syn. , meiolecithal, oligolecithal. 



EGG RECEPTOR - part of Lillie's scheme pic- 

 turing parts that go into the fertilization 

 reaction involving fertilizin. Egg receptor 

 plus amboceptor plus sperm receptor gives 

 fertilization. 



EGG, TELOLECITHAL - egg with large amount 

 of yolk concentrated at one pole. 



EGG WATER - watery extract of materials dif- 

 fusing from living (Echinoderm) eggs, pre- 

 sunnably the "fertilizin" of Lillie. Syn. , 

 egg water extract. 



EIDOGEN - a chemical substance possessing 

 the power to modify an embryonic organ 

 otherwise induced; force in regional differ- 

 entiation, possibly including inductors of 

 the second-grade level. 



EINSTECKUNG - method of testing the power of 

 induction by implanting a tissue, living or 

 dead, or a chemical substance, into the 

 blastocoel of a living gastrula. 



ELECTRODYNAMIC THEORY OF DEVELOP- 

 MENT - theory that cell mitoses establish 

 a definite differential potential capable of 

 orienting growing nerve roots (axis cylin- 

 ders) and thereby directing them (e. g. , to- 

 ward the brain). 



EMANCIPATION - dynamic segregation from 

 "autonomisation" (Weiss, 1935); establish- 

 ment of local autonomy within embryonic 

 areas. 



EMBRYO - a stage in the ontogeny of the fertil- 

 ized egg limited to the period before the 

 intake of food. 



EMBRYOMA - (See teratoma) 



EMBRYONIC FIELD - region of formative 



processes within the embryo, larger than 

 the area of ultimate realization of structures 

 concerned (Gurwitsch, 1922). 



EMBRYONIC SHIELD - thickened, shield-like 

 region of the blastoderm which will give 

 rise to the body of the (fish) embryo. 



EMBRYOTROPHY - the means or the actual 

 nourishment of the embryo. 



ENCAPSIS - superordinate system within the 



embryo. Processes may be purposeful for 

 a subordinate system and yet destroy an- 

 other system to which it itself is subordi- 

 nate. These relations are called encapsis 

 (Heidenhain). 



ENCHYLEMA - the liquid phase of the endoplasm 

 in which are suspended yolk granules and 

 rnitochondria (Monne). 



