General Notices. 365 



periineut with a black substance, the heat absorbing power of the ground 

 was so much increased as to enable it to maintain a night atmosphere round 

 the plants high enougii to repel the late frosts of Devonshire, and to main- 

 tain a healthy growth during the day. These are, we imagine, the three 

 points which have chiefly led to su -cess. It must, however, be remarked 

 that the fruit was set before the p/anis were exposed to the air. Had this 

 been neglected, we believe the experiment would have failed ; and we even 

 attribute the " blindness" of the upper part ol the fruit to the setting pro- 

 cess not having been completed there, at the time when the plants were 

 removed from shelter. 



It may be alleged that this experiment is more curious than useful ; that 

 the only practical result is that it merely enables a fruiting house to be 

 cleared in May, and immediately converted into a succession house, instead 

 of remaining full of fruiting plants till August. We, however, do not re- 

 gard it in that light. It will be highly interesting to know what sort of 

 young plants will be formed by the suckers thus obtained ; Mr. Barnes says 

 they are extremely vigorous ; we should expect them to be so ; and if they 

 continue to thrive thus during the remainder of the summer, they will prob- 

 ably become the parents of very fine fruit. This is, however, in the future. 



What in our eyes is of most practical interest is the establishment of the 

 fact, upon which we have so long and often insisted, that a high night tem- 

 perature in forcing-houses is a fatal mistake. Good gardeners are begin- 

 ning to admit the correctness of this view in vineries ; but they have 

 doubted whether the principle could be applied to the pine apple, because it 

 naturally grows in countries so much hotter than those occupied by the vine. 

 But they forget the effect of radiatittn at night ; they have not considered 

 how low the temperature of even the tropics must ofien become near the 

 surface of the ground, under the bright and cloudless skies of such regions ; 

 they have not recollected that ice is formed during the night in Bengal. 

 The new experiment of Mr. Barnes has shown that what is true of the vine 

 is equally true of the pine apple ; for, notwithstanding the efficacy of a 

 black surface, it is impossible that the temporature of the air round his 

 pines should not have been much below 40° in the "frosty mornings" of 

 which he speaks. 



Another point is the excellent flavor of the fruit thus produced. To 

 what was that owing? not to high temperature, nor to bright and long-con- 

 tinued sunshine, for we are told that the weather was stormy, with many 

 dark sunless days. It was caused by the free access of air constantly pass- 

 ing over the leaves, incessantly feeding them on the one hand, and helping 

 them on the other to elaborate their juices by the as incessant removal of 

 their superfluous water. What a lesson is this to us all ! What a condem- 

 nation of our vicious system of building glass-houses to be filled with stag- 

 nant air and vapor ; of our miseiable ventilation ; of our barbarous flues ; 

 of our water-pipes and tanks, and the sluggish atmosphere which they 

 warm. Let us even add what a triumph it is for the friends of Polmaise, 

 de luinstrating as it does the soundness of their views of the paramount im- 

 portance of rapid currents of everchanging air. For ourselves, we are per- 

 33* 



