INTRODUCTION. 7 
costly, and an even more troublesome matter, than the 
construction of the house itself. Not that a cold or 
unheated structure is by any means without its uses, and, 
indeed, for certain purposes, such as preserving calceolarias, 
pentstemons, and other nearly but not perfectly hardy 
plants during the winter, protecting the blossoms of 
Christmas roses, violets, laurustinus, the early-flowering: 
irises, hardy cyclamens, etc. ; as well as for wintering 
carnations, auriculas, ‘roses and others in pots, am 
unheated greenhouse is a really valuable addition to a 
garden. It is also by no means necessary for what are 
termed orchard-houses to be artificially heated, and some 
vines may also be grown fairly well in an unheated. 
structure, if situated in a warm and sunny position, 
though a little artificial heat is generally a very great. 
advantage in the culture of grapes of all kinds. But in 
order to obtain flowers or fruit of most descriptions in 
the winter season, to raise bedding or other plants of a. 
tender nature in good time, from seed or otherwise, not 
to mention anything of the nature of forcing, some 
amount of artificial heat is absolutely necessary. 
Further, the best and most satisfactory results, from a. 
cultural point of view, are obtainable only by having every 
structure specially constructed for and adapted to the 
particular purpose for which it is intended, and the method 
of heating ought also to be suited to the probable require-. 
ments. Houses for the growth of cucumbers, for instance, 
should be of totally different construction to those in which, 
tomatoes, pelargoniums, or the like are to be cultivated. In. 
fact, almost every class of plant in cultivation is found to. 
succeed best when grown in houses constructed specially 
