k6k GLOSSARY 



FERTILIZATION, PARTIAL - oases where sperm head, after entering the egg cortex, does not move fast enough 

 toward the egg nucleus to arrive before cleavage seta In, although the sperm aster may have reached 

 the egg nucleus and given rise to the segmentation spindle. 



FERTILIZATION, SELECTIVE - physiological block to some combinations of sperm and egg, such as in cases of 

 self-aterlllty (e.g., Clona). May Indicate differential fertilizing powers of spermatozoa even from 

 a common source. 



FERTILIZIN - chemical substance In the egg cortex of mature (Echlnoderm) eggs, called "sperm laoagglutlnln" 

 (Llllle, 1916) since its presence Is necessary for fertilization of certain forms. Supposedly 

 possesses two side chains, one apermophlle and the other ovophlle. Soluble colloidal substance 

 ( agglutinin) produced by eggs to attract sperm. 



FERTILIZIN, ANTI - "ifegs contain In their interior a substance capable of combining with the agglutinat- 

 ing group of the fertllizln, but which is separate from it as long as the egg is inactive" (Lilllel 



FEULGEN REACTION - Schlff's aldehyde test accomplished by hydrolysis of thymo-nuclelc acid to yield the 

 aldehyde which reacts with fuchsln giving a brilliant violet or pink color, a specific test for the 

 thymo-nuclelc acid of chromosomes. 



FIBRILLATION - process of formation of (collagenous) fibers by the aggregation of ultramicrona whose 

 axes are nearly parallel. May be the method of axis formation in limb rudiments (Harrison). 



FIELD - mosaic of spatio-temporal activities within the developing organism constitute fields; areas of 

 instability with positional relations to the whole organism, within which specific differentiations 

 are about to take place (e.g., heart or limb fields). Etynamlc system of interrelated parts In 

 perfect equilibrium In the undifferentiated organism. Not a definite circumscribed area (like a 

 stone in a mosaic) but a center of differentiation with Intensity diminishing with the distance from 

 the center, and with different fields overlapping (Harrison, I918). A system of patterned conditions 

 In a self-sustaining configuration (Weiss, I926). Has a material substratum which may be reduced 

 without fundamentally altering the original field pattern. Field is both heteroaxlal and hetero- 

 polar. "Morphe concept" of Gurwltsch (1911+). 



FIELD, DISTRICT - a district whose activities show field character although none of Its elements can be 

 identified with any particular component of the field. 



FIELD, GRADIENT - the direction along which the field Intensity changes most rapidly. 



FIELD, HETEROAXIAL - field in which developing structures vary along three coordinates in space. 



FIELD, HBPEROPOLAR - the effects within a field differ in two opposing senses along the same axis. 



FIELD, INDIVIDUATION - fields are under the control of the organizing forces of the host whose differentia- 

 tion leads toward the realization of a conjlete Individual. 



FIELD LAWS - (1) When material Is split off from a field bearing system, that portion remaining contains 

 the field In its typical distribution and structure. 



(2) When unorganized but labile material enters the field it is Included within the field. 

 Any field spreads over the whole of the material at its disposal, preserving its 

 initial structure even though somewhat enlarged. 



(3) Fields have the tendency of taking up and including within themselves any equivalent 

 fields from contiguous environment (e.g., whole embryos formed from two fused eggs). 

 (See Schotte, 19'+0: Growth suppl. p. 6't.) 



FIELD, MORPHOGENBTIC - embryonic area out of which specific structures will develop; fields which determine 

 the development of form in a unitary structure (Gurwltsch, 1930). 



FIELD, ORGAN - area in which a specific organ of the embryo will develop (e.g., eye field). 



FIELD, TACTIC - field governing the displacement of cells (e.g., grouping of cells in the cartilaginous 

 prlmordium of the amphibian skeleton - Anlkln, 1929). 



FIELD, VEGETATIVE - early differentiated part of the Echlnoderm embryo; presumptive endoderm. 



FOLLICLE - a cellular sac within which the egg generally goes through the maturation stages from oogonium 

 to ovum; made up of follicle cells, theca Interna and externa. 



FOVEA GERMINATIVA - pigment-free spot of the animal hemisphere where the amphibian germinal vesicle gives 

 off its polar bodies. 



FRAMBOISIA - protrusion of cells following treatment of the embryo with anlaotonic solutions (Eoux). 



FREEMARTIN - mammalian Intersex due to masculinzatlon of a female by its male partner when the foetal 

 circulations are continuous and the sex hormones are Intermingled, as In parabiosis. 



FUNCTION, HOMOLOGOUS - synchronous behaviour (e.g., when supernumerary limbs are grafted near the control 

 limb, they may acquire innervation from the plexus of the control and will thereafter contract syn- 

 chronously and with the same degree of intensity as the control) (Weiss, 1936: Biol. Rev. 2 - 

 Resonance Theory of Reflex Activity.) 



FURCHUNG - division of the egg cell into blastomeres by mitosis. 



CALVANO- NEUROTROPISM - differences in electrical potential responsible for growth and connections of 

 developing nerves. Galvanic forces in neurogenesis. 



GAMETE - a differentiated (matui*e) germ cell, capable of functioning in fertilization, (e.g., sperma- 

 tozoon, oviun. ) Syn., germ cell. 



GAMETOGENESIS - the process of developing and maturing germ cells. 



GASTROSCHISIS - improper closure of the body wall along the mid-ventral line. 



GASTRULA - the didermlc or double- layered embryo, possessing a newly formed cavity known as the gastrocoel 

 or archonteron. The two layers are ectoderm (external) and endoderm (internal) with only positional 

 significance when first formed. 



