These two periods of the year are the spring and autumn in the southern hemisphere.  The mode of cultivation is in drills, into which the root is dropped, with a little manure.  The climate, even during the summer season, is severe, scarcely a night passing over without the streams being frozen over, the sky being in general cloudless at all periods of the year except during the rainy season (December to March).  Mean temperature about 49 deg..”  This information seems to support the view formed of this plant from its behavior at Kew last year, namely, that the tubers are formed on the approach of cold weather, and that, so long as the weather is warm and bright, leaves only are developed.  Plants grown in houses where the temperature has not been allowed to fall below 50 deg. in winter did not form any tubers, although they were in good health.  We found no tubers on the plants grown out of doors till some time after the return of cold, wet weather.  It seems likely that this plant does not develop tubers unless its existence is threatened by cold; at all events, such a conclusion seems reasonable from the above statements.

Possibly a wet and rather cold autumn would be favorable to this plant and the production of its tubers—­such a season, for instance, as would be most unfavorable for the common potato.  It would be worth while testing the Ullucus for low and cold situations where the potato would not thrive.  There is not much probability of the former ever proving a substitute for or even a rival to the potato, at least in this country; but there is room for another good esculent, and the Ullucus is prolific enough, hardy enough, and, we suppose, when properly grown, palatable enough to be worthy a trial.  In the Gardeners’ Chronicle for 1848, p. 828, will be found a most interesting detailed account of experiments made with this plant in France by M. Louis Vilmorin.—­W.  Waston, Kew; The Gardeners’ Chronicle.

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