Botany and Zoology. 103 
For example, the long-styled P. Palinurii can be fertilized readily by 
pollen of the long-styled P. Auricula ; yet, after numerous trials, I have 
failed to effect a single union between the long-styled form of the P. Pa- 
dinurit and the short-style ed P. Auricula, ow utterly re 
en, are such facts with the teachings of those who wouk 
lieve that an absolute causal relation exists between the sterility from hy- 
bridism and systematic affinity! On the other hand, how unequivocally 
o these cases show us that the greater or less facility of one species to 
unite with another is, as Mr. Darwin has sagaciously argued, ‘incidental 
rious and somewhat analogous degrees of difficulty in being grafted to-” 
gether i in order to prevent them becoming inarched in our forests,’ 
a 
eapsule— hat - as two to 
ie: d with oO are the remarkable shanties! in the rb of the 
[terns] colored varie f the Primrose, the red variety y yieldin ing 
ee 
orms. 
“etiaty or not the ultimate tendency of dimorphism isa ee 
he of the sexes, I think we have the clearest testimon y that di- 
otra, the: occasional Secdisction of intermediate stages a 
adie and the normally dimorphic. These, taking us back in er 
"Origin of Speen ed, p29. 
