898 THE BOOK OF GARDENING. 



which in many cases have a- flowering period of much 

 shorter duration. Few instances can he cited of them 

 having been subjected to outdoor cultivation in this country 

 where waste steam or hot - water has been utilised for 

 increasing the temperature of the water ; but where these 

 experiments have been made they may be said to have 

 been attended with fairly satisfactory results. One has, however, 

 to seek much further for data of this kind, and in doing so to 

 gladly recognise the enthusiasm of the American cultivators of 

 tropical - Aquatics ; for it is in the United States that progress, 

 especially in latter years, has been most noteworthy, where 

 more favourable conditions prevail than those of this country, 

 the chief of them being a more suitable climate. Regarding 

 their general cultivation in this country, it is in suitably- 

 . constructed heated tanks under glass that the best results are 

 invariably attained, as these afford a choice of positions adapted for 

 the accommodation of particular kinds free from the disadvantages 

 of the too variable temperature of the atmosphere. Distributed 

 over a very wide range in tropical countries, the Nymphseas 

 include sorts which naturally present individual divergences of 

 constitution and habits of growth that the observant cultivator 

 will not fail to note, and which will provide an indication of 

 details relating to their treatment of much practical service to 

 him. ' 



During the winter months the Lily tank (Fig. 602) is least 

 attractive, but even then, provided goldfish have been introduced 

 in sufficient numbers, it is not altogether devoid of interest; and 

 these fish are decidedly an acquisition as well as being serviceable 

 in. checking confervoid growths and insect pests when the Aquatics 

 are in growth. To view a collection of these lovely tropical Lilies 

 in flower during the daytime is always gratifying, but it is then 

 only possible to see a partial display of their glories. To do so 

 in the late hours of night when the night-flowering section 

 expand their large and showy blossoms is a revelation of beauty 

 that must be seen to be fully appreciated, and there is certainly 

 a new delight to be experienced by those who may not as yet 

 have been afforded an opportunity of doing so. 



Houses. — In the construction of a house for the cultivation 

 of Tropical Nymphaeas and other Aquatics, the span-roofed 

 form is the most suitable to adopt, as this admits the greatest 

 amount of light, which is a most essential condition to their 

 successful cultivation. The roof should not be too lofty, for this 

 is also an important point in connection with the conditions to 

 be observed in their treatment. As no shading will be required, 

 it is all the more necessary that the house should be glazed 

 with good clear gla,ss, as sometimes, through the presence of 

 air-bubbles in the glass, which focus the sun's rays, heat 

 is conducted which scorches holes in the leaves, thereby 



