384 Bibliography. 



" I could not but be struck with the circumstance of one of that very tribe of 

 plants, which I had for years fruitlessly attempted to cultivate, coming up sponte 

 sud in such a situation ; and asked myself seriously what were the conditions ne- 

 cessary for its growth ? To this the answer was, — Istly, an atmosphere free from 

 soot ; (this I well knew from previous experience) : — 2dly, light : — 3dly, heat : — 

 4thly, moisture : — and lastly, change of air. It was quite evident that the plants 

 could obtain light and heat as well in the bottle as out of it; and that the lid which 

 retained the moisture likewise excluded the soot. The only remaining condition 

 to be fulfilled was the change of air; and how vsras this to be effected ? When I 

 published my accoynt in the " Companion to the Botanical Magazine," I overlook- 

 ed tlie law respecting the diffusion of gaseous bodies, described in the preceding 

 chapter, and stated that this change was produced by the variations of tempera- 

 ture, causing alternate expansions and contractions in the air surrounding the plants, 

 and which of course produced a certain but very limited effect. 



" Thus, then, all the conditions necessary for the growth of my little plant were 

 apparently fulfilled, and it remained only to put it to the test of experiment. I 

 placed the bottle outside the window of my study, a room facing the north, and to 

 my great delight the plants continued to grow well. They turned out to be Las- 

 traa Filiz-mas and Poa annua. They required no attention, the same circulation 

 of the water continuing; and here they remained for nearly four years, the Poa 

 once flowering, and the fern producing three or four fronds annually. At the end 

 of this time they accidentally perished, during my absence from home, in conse- 

 quence of the rusting of the lid, and the admission of rain water. Long before 

 this occurred, however, I procured for the purposes of experiment some plants of 

 Hijmenophyllum and Trichomanes ; and perhaps the most instructive way in which 

 I can communicate the results of my enquiries will be to select a few out of num- 

 berless experiments, in the order in which they occurred." 



We had marked for extract the descriptive list of the plants which 

 were the subjects of Mr. Ward's experiments ; but are obliged to omit 

 it, as we have already exceeded the limits of this notice. 



Residing in one of the darkest parts of London, and exposed to the 

 " vapor of smoke" and soot which completely envelopes that metropo- 

 lis, within whose limits not even a moss will fructify in the open air, 

 (with the exception of Funaria hygrometrica, which is known to have 

 an especial fondness for charcoal,) our excellent author has thus caused 

 his favorite plants to flourish around him, for his own gratification, and 

 to the admiration of those who have been privileged to witness his com- 

 plete triumph over obstacles long deemed insurmountable. With equal 

 advantage, but with greater facility, may Mr. Ward's plan be applied 

 to parlor-culture in this country, where light is abundant, the atmosphere 

 free from soot, and we have only to guard against cold, the excessive 

 dryness of the air in winter, and the exhalations of sulphurous acid gas 

 from coal fires, which when present in such minute proportions as to be 

 wholly inappreciable to our senses, are yet highly injurious to plants 

 cultivated in a dry air. 



The most important practical application of these principles, that of 

 the conveyance of living and growing plants upon long voyages, was 



