APPENDIX I 



GLOSSARY OF GENETICAL TERMS 



I intended to augment our English tongue, whereby men 

 should express more abundantly the thing that they con- 

 ceived in their hearts (wherefore language was ordained) 

 having words apt for the purpose. 



THOMAS ELYOT [Knowledge which maketh a Man Wise, 1533) 



Words are the weapons of science. They serve for defence and for attack. They 

 tell us what we know. But, if we use them aright, they also tell us what we don't 

 know, and tliis is what we especially need to be told if we are to discover some- 

 thing new. Since Genetics is now in the full flood of its discover)' a precise 

 definition of its words and their meanings seems to be a prime necessity. 



We have prepared this hst, not therefore as a record of fmal achievement, 

 but as an instrument for new advances which will call for its own reconstruction. 

 We have attached the first importance to consistency, the second to convenience, 

 and the third to the opposing claims of fitness and flexibihty. 



For the first purpose our main task has been to reconcile the teclinical habits 

 of plant and animal workers. For the second we have had to abandon archaic 

 forms, leaving merely obituary notices of many obsolete expressions and adapting 

 others to entirely new purposes. And for the last purpose we have had to recognize 

 in many cases two stages in the ontogeny of the words: the empirical or popular, 

 and the analytical or explanatory. 



This transition is nowhere better illustrated than by the word Heredity itself, 

 which was formerly applied to a Force or a Law and has now come to be applied 

 to a Process or a Substance, as the study has passed first from the empirical to the 

 abstract and then from the abstract to the mechanical and the chemical. 



The terminology of our subject began with what was needed for describing 

 the relations of parents and progeny. It now extends to Cytology and Chemistry, 

 Embryology and Physiology, Anatomy and Taxonomy, Statistics and Biometry. 

 Indeed it obviously covers the whole structure of biology, although it is con- 

 cerned only with providing the analytical framework of this structure. 



Initial Capital Letters are used in the text for terms defined elsewhere under 

 their own names. The Author references are to the first use of the term in approxi- 

 mately the same sense as that given. 



Finally, we are indebted to the following earlier works (some of which also 

 contain bibliographies and sources) for certain definitions: — 

 WILSON, E. B. 1925. The Cell in Development and Heredity, 3rd ed. New York. 

 DARLINGTON, c. D. 193?. Recent Advances in Cytology, 2nd ed. London. 

 MATHER, K. 1 946. Statistical Analysis in Biology, 2nd ed. London. 

 Also/. Heredity, 28: 71-80. 1937. 



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