204 IV' CliNKKIlKNCK INTKIlWTKi.NAI.K DK (.KM'TIl.ll l- 



SOCIOLOGICAL AND OTHER ASPECTS OF THE UNIT CHARACTER CONCEPTION 



lly A. RUGG-GUNN. M. I!.. Ch. 15. 



I.uimI.mi 



It is commonplace lliat ono of Iho mosl imporlanl IViiits of sciendiic |ii(i- 

 gross lias beon the graduai iiiifoldiiig of llic ullimate units wliicli maUe up llic 

 pmllc'ss variely of form and malorial rcvealod in Nature. The conce|)tion of Ihc 

 conslilulion of llilngs thus implied would probably in its rude beginnings dale 

 far back lo Ihe first conscious observations of early man on the heavenly bodies 

 al night, and would become a comparalively \vell established one wilh the later 

 important généralisation that the earlh itself was a huge, detached body. tloat- 

 ing in space, and not very dissimilar probably to the celeslial units around it. 

 Later still Copernicus by demonstrating the Iruth of the doctrine now known by 

 his name gave a fresh impelus to the trend of thought in this direction, which 

 now promises almost lo revert to the acute spéculations of the ancienls — Len- 

 cippus, Democritus, Epicurus, and Lucretius — concerning the plan of Ihe 

 Cosmos. A long interval elapscs and Schlieden and Schwann hâve discovered 

 the cell, the unit of organic structure, and Dalton in the atom enunciates a 

 still more ultimate unitcommon alike lo living and non-living mattcr. Finally. 

 Hei'berl Spencer, reasoning from à priori grounds conceived the existence of 

 Ihese physiological or conslilutional units, \\hich, though their full importance 

 as the agents ofheredity was not suspecledby him, really form the sul)ject mal ter 

 of our présent genelic discussions. And lo Spencer's à pi'iori arguments we 

 are now in a position to add Mendel's expérimental proof. 



MendeFs great contribution lo scienlific thought resulted from his récogni- 

 tion of the facl thaï every Somalie fealure of an organism arose from a cor- 

 rcsponding gametic représentative, and Ihe discovery itself is in essence the 

 facl Ihal when variations of a fealure meel in fertilisation ségrégation of their 

 respective représentatives occur in the gamètes of the resulling organism. 

 (iamelic ségrégation in helerozygotes is more or less universal; the correspond- 

 ing Somalie condition is, however, nol so easy to conceive, as hère we arc 

 dealing nol wilh discreet independent units, as in the case of the gamètes, bul 

 wilh Ihc complex réalisation into which the polentialilies of thèse units bave 

 dcveloped. That however Ihey are nol single units bul occur in pairs is no\\ 

 a praclically universal axiom of genetics and I venture to think that vve bave 

 sufficient évidence for the suggestion that in some cases al any rate some sori 

 of union or combinalion occurs Ijetween Ihem. The instance of the hetero- 

 zygous (blue) Andalusian fowl is a classic example which to my mind is a 

 clear indication of a mulual influence exerled by Ihe heterozygous units. 

 Even in examples illustra ting the phenomenon of dominance, there is nolhing lo 

 gainsay a degree of combinalion of the « présence » and « absence » faclors. 

 The significance of Ihe distribution of chromosomes in gamelic and Somalie 

 cells respeclively is as yet unknown but the distinction should bc liornc in miu<l 

 in consi<lcring this question. If then, in gametogenesis we hâve ségrégation of 

 unit cbaracters in somalogencsis comljination. or, to make use of a chemical 



