GLOSSARY 



ALLELOMORPH. Allelon, onc another; morpha, form. One of a pair 

 of alternative hereditary characters. The term is also applied 

 to those genes which can occupy one and the same locus upon 

 a particular chromosome. 



ANAPHASE. Ana, up; phasis, appearance. The stage at which 

 daughter chromosomes move apart in nuclear division. 



ATTACHMENT, (i) The spindlc attachment, q.v. (2) The permanent 

 fusion of two chromosomes (catination). 



AUTOSOMES. Autos, sclf; soma, body. Those chromosomes in respect 

 of which both sexes are alike. 



BALANCE, GENic. The Condition in which the genes are so related 

 and proportionally adjusted that in their action they yield 

 normal development of the organ. 



BIVALENT (see Univalent). Bis, twice; valere, to be worth. A term 

 applied to double chromosomes formed by the coupling of 

 two chromosomes especially in the process of synapsis, 



CENTROSOME. Kentroft, centre; soma, body. The self-propagating 

 body which, during mitosis in many organisms, lies at the two 

 poles of the spindle and appears to determine its orientation. 



CHROMOSOMES. Chroma, colour; soma, body. Separate, deeply- 

 staining bodies commonly rod-shaped or loop-shaped into 

 which the substance of the nuclear network resolves itself 

 during mitosis and from which the nucleus is derived at the 

 end of mitosis. 



CROSSING-OVER. The exchange of corresponding segments between 

 corresponding chromatids of different chromosomes. 



DIPLOID. Diploos, double. The zygotic number of chromosomes 

 (an) as opposed to the gametic or haploid number (n). 



DISJUNCTION. The separation of chromosomes at anaphase, par- 

 ticularly of the first meiotic division. 



FIRST DIVISION. The first of two meiotic divisions; the heterotypic 

 or reduction division. 



GAMETE. Gametes, spouse. Cells which are specialized for fertiliza- 

 tion and which normally cannot develop without it. 



GENE. Gen, to produce or producing. The unit of Mendelian 

 heredity; a hypothetical elementary entity which determines 

 the development of a particular character. To the student of 

 heredity it is that which the atom is to the chemist. 



GENOTYPE. Genus, a race; typus, an image, (i) The genetic constitu- 

 tion of an individual. (2) A class or group all the individuals 

 within which are identical in their genetic constitution. 



GYNANDROMORPH. Gyne, woman; aner, man; morphe, form. An 

 individual exhibiting a combination of male and female 

 characters. 



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