139 



tions has, so far as I can learn, not been noticed before, and such 

 variations may have but trifling significance. 



It would be interesting in this connection to know whether 

 these abnormal appearances, if we may call them such, are more 

 frequent in leaves which appear in the spring — those therefore 

 whose fundaments were laid down during the previous growing 

 season — for we might suspect that the formation of the stiff, re- 

 sistant bud scales of the winter buds, both during their first for- 

 mation and their subsequent more or less irregular early spring 

 development, would set up rather more pronounced, if not dif- 

 ferent, mechanical conditions than the scales or leaves of the 

 more evenly developing summer buds. 



I have to thank Miss Mary E. Hart for first drawing my at- 

 tention to the variations in lilac leaves, and Miss Elsie M. Kupfer, 

 who at my suggestion searched for and found a good number of 

 fine examples of the same thing. 



Teachers College, Columbia University. 



A KEY TO THE NORTH AMERICAN SPECIES 

 OF LACTARIUS— I 



By F. S. Earle 



The species of this genus are at once distinguished from all 

 other mushrooms by the flowing of a more or less abundant 

 milky juice when cut or wounded. Many of the species are ex- 

 ceedingly acrid or peppery when raw but as is the case with the 

 nearly allied Russulas this is said to disappear on cooking and 

 most of the species are considered to be edible. So far as known, 

 none of them contains a poison. As a rule they require longer 

 cooking than most other mushrooms. 



The most important paper on our American species is that by 

 Peck in the 38th Report of the New York State Museum, in 

 which he gives a synopsis and full descriptions of the species 

 known to occur in the State. Of the following seventy-six 

 species and varieties that have been reported as occurring in 

 North America thirty-one have been described by Professor 



