628 The American Naturalist. [July, 
the 22d of the same month. I also noticed a flock of about 30 in our 
apple orchard, from April 28 to May 7, 1897, and shot several individ- 
uals. 
70. Poocaetes gramineus (Gmel.), Vesper Sparrow. Abundant sum- 
mer resident. (Earliest spring arrivals: April 5,1887; March 31, 
1888 ; March 28, 1889; April 18, 1891; March 29, 1895. Bulk ar- 
rived: April 6, 1887; April 1, 1888; April 4, 1889; April 19, 1890). 
71. Ammodramus sandvichensis savanna (Wils.), Savanna Sparrow. 
Abundant migrant in the spring and fall. (Spring occurrences noted : 
April 8-13, 1886, March 28, 1889; April 19, 1890; April 18 to May 
9, 1891). 
(To be continued.) 
On the Use of the Terms Heredity and Variability.— 
Recent discussions of various biologie phases of evolution have become 
so refined that our attention must be more critically given to the exact 
meaning which each writer gives to the terms he uses. Each author, 
having some special point to emphasize, gives his own particular defini- 
tion to common terms, and so makes a direct comparison of his proposi- 
tions with those of other writers impossible. A great deal of time- 
patience-consuming controversy finds room in mere quibbles of words | 
without essential disagreement of ideas. Even the terms “ heredity ” 
and “ variability,” standing for the very foundation blocks of evolution, 
suffer seriously from this duplicity of definition. 
It has long seemed to the present writer that considerable polemic 
friction could be avoided without a re-definition of these two important 
terms if the relationship of the two notions were more accurately and 
generally apprehended. Heredity and variability are so commonly 
placed in antithesis that we unconsciously assume that they express 
qualitative differences. But they do not. In relation to each other 
their significance is purely quantitive. In the quantitive scale they 
designate supplements. If one race manifests variability more than 
another it manifests heredity by so much less. If variability increases 
in a variety heredity wanes. If the inheritance of likenesses becomes 
more marked we say that variation is growing less; our variety is be- 
coming “fixed.” Thus heredity and variability really stand to each 
other as heat and cold,—as positive and negative. Anda perfectly 
accurate nomenclature could dispense with one or the other. But 
while both terms are still conveniently retained, as are the terms heat 
and cold, it is extremely desirable that their unity of application be 
observed. 
If this complimentary nature of hotelit and várisbility were more 
keenly appreciated many evolutionary misunderstandings wouid be 
