188 ROYAL SOCIETY OF CANADA 



from without then it may be elaborated by many cells or rather by the 

 ferments of many cells. That postulates a circulation of chromatins, or 

 iron-liolding nucleoproteins, with the plasma and lymph in tlie animal 

 body and with the tissue juices in the vegetable organism. 



The iron-holding nucleo-proteins from the hepatic nuclei are dif- 

 ferent from tliose obtained from the pancreas, and the latter again are 

 different from those of the nuclei of the renal cells. The iron-holding 

 nucleo-proteins of ova must be different from those of somatic cells as 

 otherwise the latter ought to become germ-cells and tlirough fertilization 

 to reproduce the organism. 



If these iron-holding nucleo-proteins circulate in the body fluids 

 and in the juices of vegetable organisms, how may it possibly happen 

 that only one kind reaches the nuclei of the germ cells, another the hepatic 

 cell nuclei, a third the pancreatic cell nuclei and so on? The answer 

 that I would give is that the nuclear membrane in each case determines 

 what iron-holding nucleo-protein reaches the interior of the nucleus, and 

 as the nuclear membrane in the different species of cells varies in its 

 physical and, perhaps also, chemical qualities, the chromatin reaching 

 the interior of the nuclei in one type of cells, for example, the germ- 

 cells, is on the whole uniform in composition, but there may be varia- 

 tions in the character of the membrane and consequently the chromatin 

 in the' nuclei of the germ-cells may be so different as to give rise in the 

 offspring to modifications of structure of form varying from the simple 

 '■' sport " to the monstrosity. 



It is in this way easy to account for the persistence of characters 

 in a species through a long series of generations and to explain varia- 

 tion. It is possible on this basis to understand the development of the 

 cancer-cell, the origin of a second lens in the Amphibian eye after the 

 removal of the first, the power of cuttings to develop into complete adult 

 plant forms, and to comprehend natural parthenogenesis. We are in a 

 position also to understand why a liver cell gives ordinarily rise only to 

 a liver cell, and a pancreatic cell only to another of the same kind. In 

 a unicellular organism the cytoplasm elaborates one kind of iron-holding 

 nucleo-protein which is stored up in tlie nucleus, and thus there is a 

 stability of character in tliese forms, that does not obtain in the Metazoa 

 and Metaphyta. 



On this basis we do not need to postulate some mysterious force 

 keeping the germ-plasm continuous or persistent in character. The 

 theory here advanced enables us to understand how variations may arise. 

 It explains how conditions of nutrition may affect the offspring. It does 

 not require us to believe that use or disuse of an organ in a parent may 



