those of the unicellular organisms 39 



ancestral plasms, and without ancestral 

 plasms more complicated than those of the 

 Protozoa there can be none of the superior 

 animals ^" But Weismann rejects the in- 

 heritance of acquired characters and so cuts 

 oflF the first possibility : also he maintains — 

 or rather began by maintaining — the absolute 

 continuity and isolation of the germ-plasm, 

 and so cut off the second. 



Simultaneously with Delage's criticism 

 however — in 1895 that was — Weismann made 

 the complete change of front to which I 

 have just alluded, abandoning — or at least 

 essentially modifying — both his main posi- 

 tions, viz. the stability of germ-plasm and 



1 Yves Delage, L'Heredite et les grands Problem es de la 

 Biologic genSrale, 1903, p. 560. But to Professor Hartog of 

 Cork belongs the credit of first conceiving "cette objection 

 capitale sous la forme du dilemme," as Delage expressly allows. 

 Op, cit. p. 559 n. See Professor Hartog's letter in Nature, 

 vol. xliv, 1891, entitled, "A Difficulty in Weismannisra," pp. 61 3 f., 

 and a second letter, vol. xlv, pp. 102 f. 



