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GLOSSARY 



HEMIKARYOTIC - haploid. In merogony, 



hemikaryotic arrhenokaryotic androgenetic 

 or in artificial parathenogenesis, hemi- 

 karyotic thelykaryotic gynogenetic. 



HEMIMELUS - failure of distal portion of ap- 

 pendages to develop. 



HENSEN'S NODE - anterior end of the prim- 

 itive streak of the chick embryo, corres- 

 ponding to the region of the dorsal lip of 

 the amphibian egg; region of future mid- 

 brain (position). 



HENSEN'S THEORY - nerve fibers are formed 

 out of protoplasmic bridges which exist 

 throughout the embryonic body, protoplas- 

 mic bridge theory. 



HERMAPHRODITE - an mdividual capable of 

 producing both spermatozoa and ova. 



HERTWIG'S LAW - the nucleus tends to place 

 itself in the center of its sphere of activity; 

 the longitudinal axis of the mitotic spindle 

 tends to lie in the longitudinal axis of the 

 yolk-free cytoplasm of the cell. 



HETEROAGGLUTININ - agglutinin (fertilizin) 

 of eggs which acts on sperm of different 

 species, substance extractable from egg 

 water which causes irreversible agglutina- 

 tion of foreign sperm. 



HETERAUXESIS - the relation of the growth rate 

 of a part either to another part of or to the 

 whole organism. May include comparison of 

 organisms of different sizes and ages, but 

 of the same group. (See growth, heterogon- 

 ic; isauxesis, bradvauxesis, tachyauxesis. ) 



HETEROCHROMATIN - part of the chromatic 

 structure which seems to be related to the 

 formation of the nucleolus. Takes a violet 

 stain after methyl green but is digested 

 away by ribonuclease. Probably represents 

 both thymo- and ribo-nucleic acids. 



HETEROCHRONY - alteration and reversal of 

 the sequence of stages in ontogeny. 



HETEROGONY - constant differential growth 

 ratios (Pezard, 1918). 



HETEROGONY, NEGATIVE - when the growth 

 coefficient is below unity. 



HETEROGONY, POSITIVE - when the growth 

 coefficient is above unity, the parts in- 

 creasing in relative size. 



HETEROMORPHOSIS - differential morpholog- 

 ical differentiation under varying environ- 

 mental conditions wherein the major animal 

 gradient is flattened; appearance of an em- 

 bryonic organ inappropriate to its site; re- 

 generated part different from that which 

 was lost. Bateson's homoeosis or Goethe's 

 metamorphy. 



HETEROPLASIA - development of a tissue from 

 one of a different kind. 



HETEROPLEURAL - transplant to the other of 

 bilateral sides. 



HETEROPLOIDY - any deviation from the nor- 

 mal diploid nunnber of chromosomes 

 (Winkler, 1916). 



HETEROPYCNOSIS - condensation of some (sex) 

 chromosomes in gametogenesis. 



HETEROTOPIC - transplant to same side but 

 different region from the original. 



HETEROTROPHIC - acquiring nourishment from 

 without the organism. 



HIBERNATE - to spend the cold (winter) period 

 in a state of reduced activity (n. , hibernation). 

 Opposed to aestivate. 



HISTOGENESIS - the appearance, during embry- 

 onic development, of histological differentia- 

 tion; the development of tissue differentiation. 



HISTOLYSIS - the destruction of tissues. 



HISTOTELEOSIS - process by which a cell-line, 

 already irreversibly differentiated, proceeds 

 to its final histological specialization (Hoad- 

 ley). 



HISTOMERE THEORY - ontogenetic division of 

 histological systems resulting in the syn- 

 thesis of an (higher) organ (Heidenhain). 



HISTOTROPHE - the nutritive substances sup- 

 plied to the embryos of viviparous forms 

 from sources other than the maternal blood 

 stream (e. g. , from uterine glands). 



HOLOENTOBLASTIA - blastula almost entirely 

 composed of endoderm used by Herbst for 

 sea urchin larvae with nearly complete sup- 

 pression of ectoderm by lithium salts. 



HOLOMORPHOSIS - entire lost part replaced at 

 once or later. 



HOLTFRETER'S SOLUTION - now designated 

 (by Holtfreter's request) Standard Solution. 

 NaCl - 3. 5 gr. , KCl - 0. 05 gr. , CaCl2 - 

 0. 1 gr. , NaHC03 - 0. 2 gr. , H2O - 1 liter. 



HOMOIOTHERMAL - refers to condition where 

 the temperature of the body of the organism 

 is under the control of an internal mecha- 

 nisnn; the body temperature is regulated 

 under any environmental conditions. Opposed 

 to poikilothermal. Syn. , warm blooded 

 (animals). 



HOMOIOTRANSPLANTATION - transplantation 

 between different but related individuals. 



HOMOLOGOUS - organs having the same embry- 

 onic development and/or evolutionary origin, 

 but not necessarily the same function. 



HOMOMORPHOSIS - new part like the part re- 

 moved (Driesch). 



HOMOPLEURAL - transplant to some same as 

 that from which it was rennoved. 



HORIZONTAL - an unsatisfactory term some- 

 times used synonymously with frontal, lon- 

 gitudinal, and even sagittal plane or section. 

 Actually means across the lines of gravita- 

 tional force. 



HORMONE - a secretion of a ductless gland 



■which can stimulate or inhibit the activity of 

 a distant part of the biological system already 

 formed. 



HORMONE, MORPHOGENETIC - term used by 

 Needham to refer to inductors which manifest 

 distant effects. 



