238 



XXXIX. UPON THE EFFECTS OF VERY HIGH TEMPERATURE ON SOME 



SPECIES OF PLANTS. 



{Read before the HORTICULTURAL SOCIETY, December 7th, 1819.] 



HAVING constructed a forcing-house for the purpose of attempting the 

 culture of the mango, and a few other species of tropical fruits, I have 

 endeavoured to ascertain, with accuracy, the advantages and disadvan- 

 tages, of employing very high temperature during the day in bright 

 weather, and of comparatively low temperature during the night, and in 

 cloudy weather ; and I communicate the following account of my experi- 

 ments, considering the results to have been generally very favourable, 

 and where unsuccessful, not wholly uninteresting. 



A fire of sufficient power, only, to preserve in the house a temperature 

 of about 70, during summer, was employed, but no air was ever given, 

 nor its escape facilitated, till the thermometer, perfectly shaded, indicated 

 a temperature of 95 ; and then only two of the upper lights, one at each 

 end, were let down about four inches. The heat of the house was conse- 

 quently sometimes raised to 110, during the middle of warm and bright 

 days, and it generally varied, in such days, from 90 to 105, declining 

 during the evening to about 80, and to 70 in the night. 



Late in the evening of every bright and hot day, the plants were 

 copiously sprinkled with water, nearly of the temperature of the external 

 air ; and the following were the effects produced upon the different 

 species. 



The Melon. Plants of this species were trained upon a trellis near 

 the glass, which was of the best quality, and these exhibited a greater 

 degree of health and luxuriance, than I had ever before seen ; but not a 

 single flower ever unfolded ; a great profusion of minute blossoms, never- 

 theless, appeared in succession at the points of the shoots, all of which 

 perished abortively. I was much disappointed at the result of this 

 experiment ; from which I confidently expected to obtain fruit of the 

 greatest excellence. 



The Water Melon. A plant of this species, treated in the same manner 

 as the melon plants above mentioned, grew with equal health and luxuri- 

 ance, and afforded a most abundant blossom ; but all its flowers were 

 male. This result did not, in any degree, surprise me ; for I had many 

 years previously succeeded, by long continued very low temperature, in 

 making cucumber plants produce female flowers only ; and I entertain 

 but little doubt, that the same fruit-stalks might be made, in this and 



