Problems of Gametic Constitution 75 



poseful or otherwise. As far as investigation has gone all instances show that 

 the combinations are purely chance, and although the use of " selective fertiliza- 

 tion " has recently been utilized in " explaining " some results of crossing, it is 

 not as a demonstration but as interpretation. It is safe to utilize for working 

 the hypothesis that all fertilization is chance and await the demonstration of the 

 instances of selective fertilization and the discovery of the actual mechanism of 

 the process. 



One aspect of the fertilization problem that has not received the attention 

 that it deserves is the rSle of environic conditions to which the uniting gametes 

 are subjected in the production of changes in the operations of the zygote, and 

 even in the non-operation of some combinations. In this there is no selection, 

 only the physical inhibiting of action or development by conditions in the 

 medium, which, if the conditions persist, result in the elimination of the com- 

 bination, solely because it can not operate, and so ceases to exist. This is a vital 

 portion of the problem that has as yet been too little studied and may have much 

 to do in determining dominance and in other ways modify the action of the 

 combinations produced by the union of unlike gametes. The work of Tennant 

 on eehinoderm fertilizations and my modifications of the behavior by means 

 of external conditions indicate some of the possibilities in this field. Further 

 data upon this same topic is presented in the following pages. It should be 

 considered as a possible agent in the investigation of " irregular " results in the 

 products of crossing, and it is not at all improbable that the condition of the 

 somatic tissues and fluids surrounding the gametes of internally fertilized 

 organisms might well play an important role in the decision of the direction and 

 character of the ensuing processes. 



It is not unlikely that the further knowledge penetrates into these processes 

 the more frequently will the play of the conditions of the medium about the 

 point of reaction become of recognized importance, and this may involve the 

 entire organism in its medium, or the portion, or character in the system of the 

 organism, in which the surrounding portions and the external medium become, 

 in combination, the important and efiBcient agents in determinations of the 

 resultant reaction and its products. In evolution there seems, in the organisms 

 I have used, the best of reasons for utilizing this idea as one of the means of 

 attack upon otherwise difficult problems, and one that promises some measure 

 of profit. 



While one can not overestimate nor fail to admire the work of Mendel and 

 its influence upon the developments of the past decade, all too often its broader 

 implications have been lost in the desire that has apparently actuated many to 

 make of it a cult, " Mendelism," as something apart from the rest of related 

 phenomena, and attempts are made to attribute to it many things not possible 

 from the very nature of its fundamental conceptions and means of operation. 

 Some adherents have, seemingly, at least tried to make of it a highly special 

 and permanent " force " in nature. This is most unfortunate. Mendel developed 

 a viewpoint, a concept of the nature of characters, a method of analysis of the 

 problems of constitution of the organism, and of the phenomena of heredity, 

 and out of these the neo-Mendelians, especially Cukrot, have developed exten- 

 sions of the ideas of Mendel. Our understanding of the nature of the agents 

 will change from time to time; their terminology may alter, and the discovery 



