176 A Defence of Mendel's 



In his subsequent paper von Fischer declares that from 

 matings of rats in which the mothers were grey and the 

 fathers albino he bred 2017 pure albinos ; and from albino 

 mothers and grey fathers 3830 normal greys. "Not a 

 single individual varied in any respect, or was in any way 

 intermediate." 



With piebalds the same result is asserted, save that 

 certain melanic forms appeared. Finally von Fischer 

 repeats his laws already reached, giving them now in this 

 form : that if the offspring of a cross show only the colour 

 of the father, then the parents are varieties of one species ; 

 but if the colour of the offspring be intermediate or different 

 from that of the father, then the parents belong to distinct 

 species. 



The reader may have already gathered that we have 

 here that bane of the advocate the witness who proves 

 too much. But why does Professor Weldon confine von 

 Fischer to the few modest words recited above ? That 

 author has so far as colour is concerned a complete 

 law of heredity supported by copious " observations." 

 Why go further ? 



Professor Weldon "brings forth these strong reasons" 

 of the rats and mice with the introductory sentence : 



" Examples might easily be multiplied, but as before, I have 

 chosen rather to cite a few cases which rest on excellent authority, 

 than to quote examples which may be doubted. I would only 

 add one case among animals, in which the evidence concerning 

 the inheritance of colour is affected by the ancestry of the 

 varieties used." 



So once again Professor Weldon suggests that his laws 

 of ancestry will explain even the discrepancies between 

 von Fischer on the one hand and Crampe and von Guaita 



