RESISTANCE TO COLD, HEAT, ETC., IN GRAPES. 65 



hills, as is the Post-Oak grape of Texas, while those that grow 

 best in very limey soils, belong to species native in such soils. 



We find, however, that in some cases varieties of species, 

 native in very sterile soils, take on far more vigorous growth 

 when put into soils richer in humus, and the chief elements of 

 plant-food; and this causes excess of wood and leaf-growth, to 

 the detriment of fruit bearing, when carried to the extreme. 



Nearly all species of grapes are native in warm, loamy, 

 well-drained soils, and such cannot long endure with roots per- 

 manently in water, or in cold, livery, compact clays ; but a few 

 species are known that cannot long survive in soils not sub- 

 irrigated, or having growing moisture at all times. Such are 

 Vulpina, Rupestris, Cordifolia, Cinerea. Rotundifolia and 

 Simpsoni. The last-named is often found with the roots per- 

 petually submerged in the borders of swamps, and making im- 

 mense growth. In such situations, the Vinifera, native on the 

 limey hills of soutliwest Aisa, and Post-Oak grapes of the Texas 

 sand-hills, would survive only a short time. 



In land that is seapy during rainy weather and some time 

 after, but in the dry, hot summers, dries out and becomes hard, 

 no grape thrives. Cordifolia, above all other species, perhaps, 

 can endure such situations longest. 



Concerning resistance to mildews, rots, etc., it is true that 

 all species native in high arid regions are very quickly and de- 

 structively attacked by the cryptogamic parasites, when moved 

 into humid situations, where such organisms exist. For resist- 

 ance to these parasites, natives of the parasitic regions must be 

 sought. Perfectly resisting varieties in such regions, when hy- 

 bridized with nonresisting varieties, produce only partially, or 

 weakly resisting varieties. 



Take a vine from a parasitic region, loaded with the para- 

 sites of mildew and rot, and plant it in an arid region and it be- 

 comes free of these fungi, simply because the parasites must 

 have much moisture in the air to propagate. 



This law does not hold good as to root parasites, or bac- 

 terial blights that live within the cells. For example, the Ana- 

 hein grape disease, of California, thrives in the moist regions of 

 northern California as well as in the dry region of southern Cali- 



