No. 592] HYBRIDS OF GENUS EPILOBIUM 247 



from Shropshire, N. "Wales, Yorkshire, and even near 

 Edinburgh. Through the kindness of Dr. Wilmott the 

 writer was able to examine the spores of a considerable 

 number of both these varieties from specimens in the her- 

 barium of the British Museum, and in every case the 

 anthers contained a mixture of normal and abortive 

 grains. 



We have here, then, a very interesting condition— 

 wherever the two varieties of E. cmgustifolium are pres- 

 ent, the spores are partially abortive— indicating the bar 

 sinister; this state of affairs is found in England, and 

 probably in Europe, Asia and western North America, 

 where both varieties are known to coexist. Wherever, 

 on the other hand, as in southeastern North America, 

 there is but one variety, the spores are all normal. Cha- 

 mmnerion, therefore, instead of discrediting the value 

 of abortive pollen grains as a test for hybridism, affords 

 another instance of its value. It also suggests another 

 question— how far apart genetically must individuals be 

 before the spores begin to degenerate? Hitherto it has 

 been assumed that only crosses between recognized species 

 bring about that result, but in the case of Epilobmm, the 

 varietal difference appears sufficient. This, however, 

 opens up the whole question of what is a species, and can 

 not be entered upon here. 



