138 A Defence of Mendel's 



Considering also that the shapes of peas depend un- 

 questionably on more than one pair of allelomorphs I 

 fully expect regular blending in some cases. 



As however it may be more satisfactory to the reader 

 and to Professor Weldon if I follow him through his 

 "contradictory" evidence I will endeavour to do so. Those 

 who have even a slight practical acquaintance with the 

 phenomena of heredity will sympathize with me in the 

 difficulty I feel in treating this section of his arguments 

 with that gravity he conceives the occasion to demand. 



In following the path of the critic it will be necessary 

 for me to trouble the reader with a number of details of a 

 humble order, but the journey will not prove devoid of 

 entertainment. 



Now exceptions are always interesting and suggestive 

 things, and sometimes hold a key to great mysteries. Still 

 when a few exceptions are found disobeying rules elsewhere 

 conformed to by large classes of phenomena it is not an 

 unsafe course to consider, with such care as the case permits, 

 whether the exceptions may not be due to exceptional 

 causes, or failing such causes whether there may be any 

 possibility of error. But to Professor Weldon, an exception 

 is an exception and as such may prove a very serviceable 

 missile ; so he gathers them as they were " smooth stones 

 from the brook." 



Before examining the quality of this rather miscellaneous 

 ammunition I would wish to draw the non-botanical reader's 

 attention to one or two facts of a general nature. 



For our present purpose the seed of a pea may be 

 considered as consisting of two parts, the embryo with its 

 cotyledons, enclosed in a seed-coat. It has been known for 

 about a century that this coat or skin is a maternal structure, 

 being part of the mother plant just as much as the pods 



