THE HICKORY-NUTS OF NORTH AMERICA. 



75 



variety only. A second species is the pig-nut, which has a thin husk 

 but a thick shell. The kernel is small, and, though agreeable at first, 

 soon becomes bitter and disagreeable. It is never eaten by man, but 



Fig. 7. — Pig-not Hickouy ( Cart/a porcina). 



Fig. 8. 



-Notmeg Hickory {Carya myrisiiccc- 

 formis). 



used to feed hogs, or left for the wild animals. This nut is somewhat 

 variable in shape, sometimes being distinctly pear-shaped and then 

 again round. Michaux says that the same tree yields nuts as large as 

 the thumb and others as small as the little finger. The third species 

 in this same line is the nutmeg hickory, which has a somewhat rough 

 husk, with a smooth nut, lined with streaks of white, and a shell so 

 thick as to constitute one half of the whole nut. The kernel is infe- 

 rior even to the pig-nut hickory. 



If all these species were to be arranged so as to show their affini- 

 ties, something like the following diagram would result : 



Nutmeg hickory, 

 \ 



Pig-nut hickory, 



Mocker-nut, 



Small-fruited hickory, Thick shell-bark, 



\ / 



White shell-bark, 



i 



Bitter-nut, 



i 



Water-hickory. 



From facts already given it will at once be apparent that two feat- 

 ures in the nuts are correlated. The thick-shelled nuts have sweet ker- 

 nels, though they differ in edibility, and the thin-shelled ones are inva- 

 riably bitter. Thus the sweet ones protect their kernels by incasing 

 them in hard shells — a precaution unnecessary for those whose kernels 

 are bitter, because they are protected by this feature alone. 



There remains, now, one species to be considered, and that is the 

 pecan. While the white shell-bark seems to occupy a central place 

 among the species, the pecan is intermediate between the hickories 

 and the walnuts. These two genera, Carya and Juglans, as botan- 

 ists know them, constitute the main part of the order to which they 

 belong. When two genera are as closely allied as these are, an evo- 

 lutionist accords a common origin to both. In fact, the difference 

 between the two is a technical and comparatively an unimportant one. 



