SPECIFICITY IX FERTILIZATION 



20Q 



extensive set of trials involving over six hundred fertil- 

 izations Morgan found very considerable variations in the 

 percentages of fertilization in different combinations. 

 The experiments were usually conducted with groups of 

 four or six individuals and involved all reciprocals and 

 the self-fertilizations in each case. While all the results 

 cannot be regarded as equally free from error, they 

 nevertheless justify the conclusion, when taken together, 

 that there are verv considerable variations with refer- 

 ence to fertilizing power in different combinations, even 

 reciprocal ones, in spite of Fuchs's criticism of this 

 result. 



It may be pointed out that the problem of indi- 

 vidual incompatibility is not necessarily associated with 

 hermaphroditism and the problem of self-sterility; it 

 is probable that there is a considerable amount of indi- 

 vidual variation with respect to gamete compatibility 

 in species with separate sexes, though little is known on 

 this point. 



Even when self-fertilization succeeds, the viability 

 of the resulting larvae is relatively slight, although, as 

 will be seen from the following table (after F'uchs), the 



