60 CALIFORNIA ACADEMY OF SCIENCES. 



Variations may be caused chiefly by the response of the 

 organism, or of its parts, to influences external either to 

 the organism as a whole or to the parts thus affected. 

 Or (3) variations may, as in the first instance, be wholly 

 independent of external influences, but due, not to the 

 selection of such modifications as happen to be suitable, 

 but to inherent properties of the organism itself, or to 

 predetermined properties of the combinations of organ- 

 isms. It is Nageli who advanced the first part of this 

 third hypothesis, while Morgan's organic combination 

 theory would, if pushed to its logical conclusion, it seems 

 to me, lead to the second part. If certain combinations 

 must inevitably lead to certain fixed and definite results, 

 regardless of environment, not only the incipient stages 

 but also the more advanced condition of an organism 

 should be due exclusively to the operation of this force. 

 In reality there are but two alternatives in regard to 

 the origin of variations. They are due either to some 

 force or tendency or property resident within the organ- 

 ism itself, whether it be Weismann's sexual combination 

 of different germ-plasmas, Nageli's idioplasm with the in- 

 herent tendency to vary in the right direction, or Mor- 

 gan's organic compound of sexually different elements 

 which must on uniting produce a new given result; or to 

 the workings of forces outside of the whole organism or 

 of the parts affected. The possibility, of course, exists 

 of both alternatives being valid. There is, however, a 

 very fundamental objection to the first class of forces as 

 being sufficient to originate variations, viz.: that it is at 

 variance with the law of the conservation of energy, as 

 suggested by Ryder, that an organism can create any- 

 thing new within itself without the aid of any force ex- 

 ternal to it — a feat no less difficult than for a man to 

 lift himself by the straps of his boots. The delusion of 

 supposing that it is only a very little which is created 

 new each time onlv serves to confuse the mind. 



