LITERARY NOTICES. 



419 



announces that upon further investigation he 

 believes that germ-plasm is universally un- 

 stable ! 



When this recantation occurred, Dr. Ro- 

 manes considered for a while whether he 

 should cancel the first two chapters of this 

 book already prepared for publication. He 

 concluded, however, to let them stand, justly 

 observing : " It is open to question whether 

 an author of any kind should suffer an elab- 

 orate system of theories to be published and 

 translated at the very time when he is him- 

 self engaged in producing another work show- 

 ing the untenable character of their basal 

 premises. ... At the least he should have 

 added notes to his Polar Bodies and Amphi- 

 mixis to let the reader know his change of 

 doctrine." 



It might be supposed when these leading 

 features were stricken out from Prof. Weis- 

 mann's theories of descent and evolution, the 

 remainder would be characterless. But the 

 fanciful mechanism of heredity was retained, 

 the difference in mortality between the Meta- 

 zoa and Protozoa was emphasized, and the 

 instability of germ-plasm was confined to the 

 least possible degree, still making amphimix- 

 is the main cause of variation. This disturbed 

 Dr. Romanes more than all else. He chafed 

 at " a germ-plasm that is both stable and un- 

 stable at the same time," and writes, " It is 

 this half-turn to which I object, as unwar- 

 ranted m logic and opposed to fact." 



The subject of the inheritance of acquired 

 characters, associated with the name of Weis- 

 mann, is not taken up by the author of this 

 dissertation, except incidentally, but is re- 

 served for a future volume, when it will be 

 discussed as a matter of fact. The major 

 part of the book is devoted to a consideration 

 of Weismann's theories in comparison with 

 the hypotheses of Darwin and Galton. 



According to Darwin the substance of 

 heredity, gemmules, may be formed anew in 

 each generation ; is discontinuous, and pro- 

 ceeds from the somatic to the germ cells, i. e., 

 centripetally, whence the inheritance of ac- 

 quired characters is habitual. 



With Galton the substance of heredity, 

 stirp, is mainly continuous ; proceeds from 

 germ cells outward to somatic cells, or cen- 

 trifugally. Acquired characters are rarely 

 inherited. 



Weismann taught that the substance of 



heredity, germ-plasm, was perpetually con- 

 tinuous ; proceeded from germ cells to so- 

 matic cells, centrifugally. Acquired charac- 

 ters can not be inherited. 



With the modifications recently made, this 

 theory substantially coincides with Galton's. 

 Originally, Weismann held that the sphere of 

 germ-plasm was entirely restricted and local- 

 ized ; that there was no reciprocal action be- 

 tween it and body substance ; but afterward, 

 upon being confronted with the botanic phe- 

 nomena involved in cutting, budding, and 

 graft-hybridization, he allowed that germ- 

 plasm might be found in the nuclei of so- 

 matic cells, diffused in the cellular tissue of 

 plants. 



Wrapped up also in the tenet of unalter- 

 able stability was the origin of hereditary in- 

 dividual variation, which was thus referred 

 to the Protozoa, amphimixis being the only 

 possible cause of congenital variation among 

 multicellular organisms. 



In the germ-plasm these dogmas were 

 molted as follows : " The cause of hereditary 

 variation must lie deeper than this. It must 

 be due to the direct effects of external in- 

 fluence on the biophores and determinants ; 

 . . . the origin of a variation is equally inde- 

 pendent of selection and amphimixis, and is 

 due to the constant occurrence of slight in- 

 equalities of nutrition in the germ-plasm." 



These sentences, which undo so much of 

 Weismann's distinctive theories, were, accord- 

 ing to Dr. Romanes, unnoticed by most of his 

 critics. It may be added that the differentia- 

 tion of doctrine is thus reduced to ctntripetal 

 heredity, Galton and Weismann ; centrifugal 

 heredity, Darwin and Spencer. 



Weismann's mechanism is extremely elab- 

 orate, including nine circles of germ-plasm : 

 molecules, biophores, determinants, ids, 

 idants, idioplasm, somatic idioplasm, morpho- 

 plasm, and apical plasm. Of these hypothetical 

 divisions Dr. Romanes would adopt the ids 

 and determinants, since it is a group of cells 

 rather than a single cell that varies in de- 

 scent. 



Two appendices are added to the book. 

 The first contains an argument as to whether 

 a centrifugal theory, germ-plasm, is more con- 

 ceivable than a centripetal one, pangenesis. 

 Dr. Romanes concludes that one is no more 

 imaginable than the other ; " that, whatever 

 the mechanism of heredity may be, it is at 



