164 



SCIENCE 



[N. S. Vol. XXXIII. No. 840 



on afterwards as usual; but if not sheared, the 

 wool detaches in flakes, and short shining hair 

 like that of a goat is produced afterwards. This 

 curious result seems merely to be an exaggerated 

 tendency natural to the Merino breed, for as a 

 great authority, namely, Lord Somerville, re- 

 marks, " the wool of our Merino sheep after shear 

 time is hard and coarse to such a degree as to 

 render it almost impossible to suppose that the 

 same animal could bear wool so opposite in 

 quality, compared to that which has been clipped 

 from it; as the cold weather advances, the fleeces 

 recover their soft quality." As in sheep of all 

 breeds the fleece naturally consists of longer and 

 coarser hair, covering shorter and softer wool, the 

 change which it often undergoes in hot climates 

 is probably merely a case of unequal develop- 

 ment; for even with those sheep which like goats 

 are covered with hair, a small quantity of under- 

 lying wool may always be found. In the wild 

 mountain sheep (Ovis mountana) of North Amer- 

 ica there is an analogous change of coat;'° the 

 wool begins to drop out in early spring, leaving 

 in its place a coat of pelage quite different in 

 character from the ordinary thickening — -for in- 

 stance, in the horse, the cow, etc., which shed 

 their winter coat in the spring. 



The fact of there being wool-bearing 

 sheep in the hot plains of India is not 

 necessarily a contradiction of the general 

 law, because the tendency to change may 

 be counteracted by careful selection.^" 



M. Lasterye, after discussing this subject, sums 

 up as follows : " The preservation of the Merino 

 race in its utmost purity at the Cape of Good 

 Hope, in the marshes of Holland, and under the 

 rigorous climate of Sweden, furnishes an addi- 

 tional support of this my principle, that flne- 

 wooled sheep may be kept wherever industrious 

 men and intelligent breeders exist. 



If we remove a plant to a climate where 

 frosts occur earlier, the chances are very 

 good that the plant will be killed before 

 the seeds ripen. If the variety is to sur- 

 vive, an early-ripening form must develop. 

 This actually happens with wheat.^^ 



" Audubon and Bachman, " The Quadrupeds of 

 North America," 5, 365, 1846. 



" Darwin, " Animals and Plants under Domes- 

 tication," 2d ed., 1, 103, 1890. 



" Darwin, " Animals and Plants under Domes- 

 tication," 2d ed., 1, 333, 1890. 



Wheat quickly assumes new habits of life. The 

 summer and winter kinds were classed by Lin- 

 naeus as distinct species; but M. Monnier has 

 proved that the difference between them is only 

 temporary. He sowed winter wheat in the spring, 

 and out of one hundred plants four alone pro- 

 duced ripe seeds; these were sown and resown, 

 and in three years plants were reared which 

 ripened all their seed. Conversely, nearly all 

 plants raised from summer wheat, which was 

 sown in autumn, perished from frost; but a few 

 were saved and produced seed, and in three years 

 this summer variety was converted into a winter 

 variety. Hence it is not surprising that wheat 

 soon becomes to a certain extent acclimatized, and 

 that seed brought from distant countries and 

 sown in Europe, vegetates at first or even for a 

 considerable period, differently from our Euro- 

 pean varieties. In Canada the first settlers, ac- 

 cording to Kalm, found their winters too severe 

 for winter wheat brought from France, and their 

 summers often too short for summer wheat; and 

 they thought that their country was useless for 

 corn crops until they procured summer wheat 

 from the northern part of Europe, which suc- 

 ceeded well. 



Another interesting case is that of corn, 

 also cited by Darwin.^^ 



The tall kinds grown in southern latitudes, 

 and therefore exposed to great heat, require from 

 six to seven months to ripen their seed; whereas 

 the dwarf kinds, grown in northern and colder 

 climates, require only from three to four months. 

 Peter Kalm, who particularly attended to this 

 plant, says, that in the United States in pro- 

 ceeding from south to north, the plants steadily 

 diminish in bulk. Seeds brought from lat. 37° in 

 Virginia, and sown in lat. 43°-44° in New Eng- 

 land, produce plants which will not ripen their 

 seed, or ripen them with utmost difiBculty. So it 

 is with seed carried from New England to lat. 

 45°-47° in Canada. By taking great care at first, 

 the southern kinds after some years' culture 

 ripened their seed perfectly in their northern 

 homes, so that this is an analogous case with 

 that of the conversion of summer into winter 

 wheat, and conversely. When tall and dwarf 

 maize are planted together, the dwarf kinds are 

 in full flower before the others have produced a 

 single flower, and in Pennsylvania they ripen 

 their seeds six weeks earlier than the tall maize. 

 Metzger also mentions a European maize which 



" " Animals and Plants under Domestication," 

 2d ed., 1, 341, 1890. 



