A Virginia correspondent says: "Referring to your notes on decay of varieties of strawberries (page 271), why is the spread of fungus troubles 'more fairly to be attributed to climatic causes' than to a combination of soil and climate? Do not soil and climate mutually re-act upon and affect each other? Or, do you hold to the theory that varieties have a limited existence and their descendants decay about the time the parent plant should wear out?"

[There is no evidence that we know of that varieties "run out" in the general acceptation of that term, which is that a tree or plant is but an individual, and that a cutting or graft from it does not extend the time that the individual was appointed to live. But horticulturists do know that when varieties are moved to soil or climate, or both, unfavorable to health, they do wear out, run out, or in some way become unhealthy and finally disappear. For instance, a strawberry or gooseberry in a cool moist summer climate just adapted to its constitution by nature, will not get the spot on the leaf of the one or mildew on leaf and fruit in the other. There is no known reason why a variety there should not last several hundred years. In hot dry summer climate these fungous diseases rapidly develop, and the variety soon gets poor. Hence we have to be repeatedly introducing varieties that will be " free from mildew" and "thoroughly hardy," till a few years under the enervating influences make them as bad as their predecessors. In the North where the summer climate is moist we do not hear of strawberries running out, though they grow in many varied soils. Hence it is a fair inference that soil has much less to do with the failure than climate.

Stdl our correspondent's point that unfavorable soil may sometimes be a factor in the unfavorable result is undoubtedly correct. - Ed. G. M].