222 



ried excursions ; and specimens so collected generally form the only 

 materials with which is reared many a plausible hypothesis relating 

 to specific distinction or identity. But now the student may have 

 his plants living under his own eye — may watch their growth 

 from day to day — from hour to hour. In the case of a fern, he may 

 scatter its sporules and observe the first appearance of the slightest 

 possible tinge of green on the surface of the soil ; then after a time he 

 will note the expansion of the first seedling fronds ; and so step by 

 step proceeds the progi'ess of development, until he perceives with 



dehght — 



" Each stem and leaf wrapped small, 

 Coil'd up within each other 

 Like a round and hairy ball." 



Then again how closely may he 



" Watch that ball unfolding 



Each closely nestling curl, 

 And its fair and feathery leaflets 

 Their spreading foims unfurl ! " 



And all this pleasure and instruction he may secure, even in the most 

 impure atmosphere, by the simple expedient of surrounding his pro- 

 teges with glass, which, while it allows of the free passage of light, 

 — a most essential condition in the culture of plants, effectually 

 prevents the access of fuhginous matter and loss of moisture by 

 evaporation, and at the same time ensures a calm atmosphere and 

 a more equable temperature. 



In the treatise before us Mr. Ward has published the results of his 

 thirteen years' experience in the mode of growing plants in closely 

 glazed cases. The work is divided into six chapters, and the con- 

 tents of these we give below. 



Chap. I. — On the Natural Conditions of Plants. Unless we pos- 

 sess some knowledge of the conditions which regulate the growth of 

 plants in a state of nature, it is evident that our treatment of them in 

 cultivation must be more or less defective. These conditions vary in 

 an almost endless degree ; plants being " influenced by the atmo- 

 sphere, heat, light, moisture, varieties of soil, and periods of rest." 

 The growth of plants is most sensibly affected by the purity or impu- 

 rity of the atmosphere : the heat to which they are subjected has a 

 range, at different seasons and in different countries, of not less than 

 150° : the intensity of light " varies from almost total darkness to a 

 light double that of our brightest summer's day :" then again " the 



