924 



SCIENCE. 



[N. S. Vol. XI. No. 285. 



not be transmitted ; if, on the other hand, 

 they are affected, the next generation will 

 show the efiTect. We have further seen that 

 in the case of sexual reproduction a modifi- 

 cation of the reproductive organs will, be- 

 cause of the intervention of conjugation, 

 appear as an increase in genetic variability 

 only. How will the matter stand in the 

 case of asexual reproduction ? First, with 

 regard to modifications which do not affect 

 the reproductive system — they, as in sexual 

 reproduction, will not be transmitted. Sec- 

 ondly, as regards modifications which do 

 aff"ect the reproductive organs — they will be 

 transmitted, i. e., they will affect the next 

 generation ; and the question arises, how 

 will they be transmitted? For here we 

 have the opportunity wanting in the case of 

 sexual reproduction of studying the trans- 

 mission of modifications of the reproductive 

 system without the complications intro- 

 duced by the act of conjugation. 



In considering this matter, it must be re- 

 membered that the reproductive organs are 

 with regard to external influences exactly as 

 any other organ. They can be modified 

 either directly or indirectly, though they 

 are in animals often less liable to direct 

 modification by reason of their internal 

 position.* These modifications may, as in 

 the case of other organs, be obvious to the 

 eye of the observer, octhey maybe so slight 

 as only to be detected by an alteration of 

 function, l^ow, in the case of the repro- 

 ductive organs this alteration of function 

 will show itself in the individuals of the 

 next generation (if not before) which pro- 

 ceed directly and without any complication 

 from the aifected tissue. How will these 

 individuals be aifected ? Will they all be 

 affected in the same kind of way or will 

 they be affected in different ways ? Finally, 

 will the modification last their lives only, or 



* How far the abnormal position of the testes of 

 mammalia may receive its explanation in this con- 

 nection is a question worthy of consideration. 



will it continue into subsequent asexually 

 produced generations ? 



Let us endeavor to answer these ques- 

 tions : 



(1) How will the offspring be affected ? 

 That will depend entirely upon how the 

 reproductive organ was affected. Will the 

 modification in the offspring have any adap- 

 tive relation whatever to the external cause? 

 Now here we have a capital opportunity, 

 an opportunity not afforded at all by sex- 

 ual reproduction, of examining by experi- 

 ment and observation the Lamarckian po- 

 sition. My own opinion is that there will 

 be no relation of an adaptive kind between 

 the external cause and the modification of 

 the offspring. For instance, let us imagine, 

 as an experiment, that a number of par- 

 thenogenetically reproducing organisms are 

 submitted to a temperature lower than that 

 at which they are accustomed to live. Let 

 us suppose that the cold affects their repro- 

 ductive organs and produces a modification 

 of the offspring. Will the modification be 

 in the direction of enabling the offspring to 

 flourish in a lower temperature than the 

 parent ? My own opinion, as I have said, 

 is that there will probably be no such ten- 

 dency in the offspring, if all possibility of 

 selection be excluded. But that is only an 

 opinion. The question is unsettled, and 

 must remain unsettled until it is tested upon 

 asexually reproducing organisms. 



(2) Will they all be affected in the same 

 kind of way ? Yes, presumably they will. 

 I arrive at this conclusion, not by experi- 

 ment, but by reasoning from analogy. In 

 the case of other organs of the body, the 

 same external cause produces in all indi- 

 viduals acted upon, roughly speaking, the 

 same kind of effect, e. g. , action of sun upon 

 skin, effect of transplanting maize, Porto 

 Santo rabbits, etc. The question, however, 

 cannot be settled in this way. It requires 

 an experimental answer. 



(3) Will the modification last beyond 



