FERNS. 37 



here in a healthy state. These cases, frequently 

 furnished by the extreme liberality of Dr. Wallich, 

 the enterprising and scientific director of the Hon. 

 Company's gardens in the neighbourhood of Calcutta, 

 form on shipboard a source of great interest to the 

 passengers of a four-months' voyage, and, after hav- 

 ing deposited their precious contents on our shores, 

 return again by the same ship filled with the common 

 flowers of England, 



" That dwell beside our paths and homes," 



which our brethren in the East affectionately value 

 by association above all the brilliant garlands of their 

 sunny sky. 



This interchange of sweets was a few years ago 

 almost unattainable, the sea-air and spray, as is well 

 known, being most injurious to every kind of plant ; 

 but their evil effects are now completely avoided by 

 these air-tight cases, which admit no exterior in- 

 fluence but that of light. Without entering into any 

 deep physiological explanation, it may be enough to 

 say that vegetable, unlike animal life, does not 

 exhaust the nutritive properties of air by repeated 

 inhaling and exhaustion ; so that these plants, aided 

 perhaps by the perfect stillness of the confined atmos- 

 phere, so favourable to all vegetation, continue to 

 exist, breathing, if we may so say, the same air, so 

 long as there is moisture enough to allow them to 

 deposit every night a slight dew on the glass, which 

 they imbibe again during the day. The soil is moist- 

 ened in the first instance, but on no account is any 



