12G ORGANIC EVOLUTION — THE FACTORS 



naturally be expected to spread, in time, through the 

 whole mass" (p. 40). 



But how is the transmission of acquired characters 

 thereby rendered less mysterious ? Supposing an 

 elephant exercises his trunk to such an extent that 

 the muscles enlarge beyond the ordinary, do the 

 molecular changes in this case differ essentially from 

 the molecular clianges which occur in the trunk of an 

 elephant that uses his trunk to such an extent only 

 that the muscles of it are maintained at the ordinary 

 standard ? And if they do differ, how can these 

 molecular changes, spreading through the mass by 

 way of many variously differentiated structures, which, 

 beinff of different molecular constitutions, must be 

 differently affected by the molecular changes, so affect 

 the molecular constitution of the germ cell when they 

 reach it, that it ultimately proliferates into an organism 

 with enlarged muscles in the trunk ? It must be 

 remembered, that neither muscle cells nor any of the 

 other kinds of tissue present in the trunk exist in the 

 germ cell. These only appear in its very remote cell- 

 descendants. If anything the mystery is deepened 

 by Mr. Sedgwick's theory, and those who hold that 

 acquired variations are transmitted will I think prefer 

 Mr. Darwin's theory of gemmules, or Mr. Spencer's own 

 theory of physiological units, as furnishing more probable 

 explanations. Moreover, though Mr. Sedgwick may 

 have established that other cells besides nerve cells 

 are connected by fine protoplasmic processes, he has 

 not as yet established that their nuclei are in any way 

 affected by the connection ; for example, he has not 

 proved that the nuclei of the germ cells are in any way 

 affected by the supposed partial continuity of their cell- 

 bodies with the cell-bodies of adjacent somatic cells, 

 and until this is done his researches, however interesting 



