Genetics in the Universities

Abstract

THERE are two technically distinct branches of experimental biology: physiology and genetics. The first is concerned with the processes by which life is maintained and developed, the second with the determinants of these processes which are identifiable in heredity. The distinction between the two methods of analysis is convenient, but not of course rigorous; experimental embryology attempts to connect them. Across this subdivision cuts the much older one between botany and zoology. However difficult it may be to draw the line between plants and animals, in descriptive work it is clearly necessary to draw a line somewhere. But in experimental analysis it is not merely unnecessary; it is often destructive. This is perhaps not so true in physiology as in genetics, since there is a bifurcation in the method of development of plants and animals and even in the molecular structures used in their development. But this bifurcation begins outside the cell nucleus. Within the nucleus the distinction between plants and animals in structures both molecular and super-molecular to a great extent breaks down. Nuclear division and sexual heredity are the same in principle in the fly and the flowering plant.