IX.] EVOLUTION OF THE GLASS HOUSE. 213 



of the modern building. Large glass, low, straight 

 roofs, light frames, simple foundations, small wrought - 

 iron pipes, portable automatic heaters, — these are the 

 innovations which have given the cheap greenhouse a 

 gi'eater popularity and practicability in America, prob- 

 ably, than anywhere else in the world. Yet many of 

 these features would have been heresies when Leuchars 

 wrote his excellent book in 1850. 



The simplification and popularization of glass 

 houses has simplified the management of plants in 

 them. Even laymen are now taking to greenhouse 

 plant growing, and many of them achieve most grati- 

 fying results. The first days of the commercial forc- 

 ing of plants are still within the memory of many 

 of this audience ; and it is only within the present 

 decade that great attention has been given in this 

 country to the forcing of tomatoes, cucumbers, car- 

 nations, and many other plants. The business is yet 

 in its infancy. The greenhouse has also exerted a 

 marked influence upon the plants which are grown in 

 them. There has now appeared a list of varieties of 

 various plants which are especially adapted to the 

 purposes of forcing; and this phenomenon is prob- 

 ably the most important and cogent proof of con- 

 temporaneous evolution. 



If one were asked off-hand what is the most con- 

 spicuous recent advancement in horticulture, he would 

 undoubtedly cite the advent of the sprays for destroy- 

 ing insects and fungi. These are not only eminently 

 effective, but they were perfected at a time when dis- 

 may had overtaken very many of our horticulturists, 

 and they have inspired new hope everywhere, and 

 have stimulated the planting of fruit and ornamen- 



