846 LIFE : OUTLINES OF GENERAL BIOLOGY 



course to continue itself, in whatever piecemeal fashion. The focus 

 of this picture is on the integrating of proteins which "find them- 

 selves", and gradually establish function and form as a still very 

 simple organism suggests. 



The late Prof. Minchin, in his presidential address to the Zoological 

 Section of the British Association meeting in Manchester in 1915, 

 elaborated a theory of the early stages in the evolution of organisms 

 which stands in marked contrast to that usually held. The usual 

 view starts with units of protoplasm and supposes a secondary 

 differentiation of the characteristic nuclear material, chromatin. 

 Prof. Minchin thought it more reasonable to start with little cor- 

 puscles of chromatin, which subsequently gave rise to forms with 

 a surrounding matrix of protoplasm. The nucleus or kernel of a cell 

 is rich in this very complex protein material, chromatin, a protein 

 with a considerable percentage of phosphorus, which plays a 

 leading part in vital processes. It occurs in many cases in the form 

 of definite bodies or chromosomes, constant in number and often 

 specific in shape. When the cell divides, the chromatin is divided 

 and usually with extraordinary precision, between the two daughter- 

 cells. Thus Prof. Minchin was inclined to regard the chromatin as 

 more fundamental than any other constituent of a living unit. Its 

 presence in the nucleus of the cell is invariable, and grains of it are 

 often present in the extra-nuclear cell-substance or cytoplasm as 

 well. 



"I regard the chromatic elements", Minchin said, "as being those 

 constituents which are of primary importance in the life and evolu- 

 tion of living organisms mainly for the following reasons: the 

 experimental evidence of the preponderating physiological rdle 

 played by the nucleus in the life of the cell; the extraordinary 

 individualisation of the chromatin-particles seen universally in 

 living organisms, and manifested to a degree which raises the 

 chromatinic units to the rank of living individuals exhibiting specific 

 behaviour, rather than that of mere substances responsible for 

 certain chemico-physical reactions in the life of the organism; and 

 last, but by no means least, the permanence and, if I may use the 

 term, the immortality of the chromatinic particles in the life-cycle 

 of organisms generally." (Report Brit. Assoc, 1915, p. 451.) 



The hypothetical primitive organisms which Prof. Minchin 

 started with, calling them Biococci, were very minute specks or 

 globules of chromatin, or of some allied substance. He supposed 

 that they were able to build up protein-molecules from simple 

 inorganic compounds, that they reacted upon their environmental 

 medium by means of ferments secreted by their own substance, that 

 they multiplied by dividing into a dumb-bell shape, and that different 

 kinds had their distinct specificity or individuality. 



From these "Biococci" as starting-point, a bacterial type of 



