36 



p>otatoes, if placed for a fortnight in a cold chamber 

 slightly above freezing point will readily develop when 

 planted. A similar treatment is advantageous for 

 rhubarb plants which are to be forced. Lift them out of 

 the ground and let them dr}' and be exposed to light 

 autumn frosts and they will then respond more readily 

 to methods of forcing. This practice of thoroughly cool- 

 ing plants which are to be forced is now regularly used 

 m the case of bulbs, retarded Lily of the Valley crowns, 

 Lilacs, Spireeas, etc. Abroad, other methods have come 

 into vogue with the same object m view. It has been 

 found that the mimersion of the branches of plants for ten 

 to twelve hours in a hot-water bath of from 85 deg. to 

 100 deg. Farenheit, has a remarkable etrect in accelerating 

 the unfolding of winter buds. The roots should not be 

 so treated. It is therefore best to invert the plants and 

 allow the stem and branches to hang down into the hot 

 water. The effect of the latter is quite local ; so that 

 when partially immersed only those buds which have been 

 under water are affected. Six weeks after this treatment 

 lilacs will be 111 full bloom, if subsequently grown in the 

 usual wa}'. Professor j ohannsen, of Copenhagen, has dis- 

 covered that exposure of plants to ether vapour for twenty- 

 four to forty-eight hours has a similar accelerating effect. 

 Both methods are largely used on the continent. 



Let us now consider the struct (ire of Hoivers and the 

 fitnctioji of their various farts. So manifold is the 

 appearance of flowers that it might seem at first difficult 

 in a short space to make any general statement on their 

 structure ; yet as regards the essential organs of reproduc- 

 tion we find considerable agreement. It is more par- 

 ticularly in the structure of the brightly coloured petals 

 that w^e find great variety, and largely owing to the 

 adaptation of the flowers to the visits of insects. The 

 colour and scent is developed to direct them to the hone\' 

 which the flowers provide, and special honey guides, spots 

 in the Rhododendrons and lines 111 Tansies and Violas, 

 as well as difl'erences in colour, guide them to the nectaries. 

 In making their way to these the insects come in contact 

 vnth the delicate stamens of the fiower and the pollen 

 contained m the pollen sacs at the tip of the stamen 

 becomes dusted on to the insect. Vlien it visits the next 

 flower, some of this pollen will be dusted off on the stigma 

 at the top of the immature seed vessel, and thus the insect 



