22 CALIFORNIA ACADEMY OF SCIENCES. 



According to Ryder's hypothesis acquired characters 

 must be inherited, but this hypothesis not yet having 

 been demonstrated does not afford a proof that such 

 characters are inherited. Morgan, on the contrary, 

 points out the difficulty of framing an intelligible theory 

 which will satisfactorily explain such inheritance, al- 

 though at the same time claiming that there is no theo- 

 retical evidence against it. This being the state of 

 opinion in regard to the theories, it will be well to look 

 to the so-called proofs of the inheritance of acquired 

 characters; but before so doing one other theory of 

 Weismann's bearing upon the subject must be examined, 

 viz: panmixia, or "pammixis," according to the cor- 

 rected version. 



Panmixia, according to Weismann, means the " sus- 

 pension of the preserving influence of natural selec- 

 tion," over an organ, part or function no longer 

 necessary for the welfare of the species. So far all very 

 well. We cannot quarrel with Weismann for giving a 

 name to this cessation, but we can disagree with him as 

 to the result which will be brought about; and this 

 Lloyd Morgan has done so ably that I cannot do better 

 than refer the reader to the passage."^" Weismann claims 

 that by this failure on the part of natural selection to 

 maintain the standard of excellence of an organ, it will 

 degenerate and ultimately disappear. Lloyd Morgan 

 shows that pammixis can only produce a reduction from 

 the survival mean to the birth mean. Selection, by 

 eliminating such individuals as possess inferior parts, 

 makes the standard of excellence of the survival mean 

 considerably above the standard of birth mean. If 

 then, selection cease to operate, the birth mean stand- 

 ard will be again restored. Or, to express it in figures, 



*Animal Life and Intelligence, p. 189. 



