GRAY 



Ins per-onahtyand influence prevented any great defec- 

 tion. At the present time, llio pendulum seems to have 

 v\Miii_' 1 . t' ( I ; .stiMiie. Species are small dis- 

 jm . I' iid to make many rather 



li, M 1 lie a decade or more before 



th " k to the^uiddle point, where 



I I naturalist. He was one of 



ti I I Iran naturalists to espouse 



t* I > « in's "Origin of Species." 



Ill III)- 1 I I h I ^1 111 bold contrast to his great 



coUea^'iii' A-a--i/. (Jia>'s influence was the greater 

 because he was known to be a pronounced theist. He 

 entered the conflict which arose between organic evolu- 

 tion and theology, and did much to heal the schism. 

 His wutm^'s on the evolution controversies were pub- 

 lished m two volumes, "Darwiniana" and "Natural 

 Science and KeliKion." 



Gray was a constructive philosopher, as well as a 

 critic. His essay on the "Relations of the Japanese 

 Flora to that of North America," was one of the flrst 

 masterful attempts to explain the principles of the dis- 

 tribution of species. This essay stands for the following 

 conceptions: that species ha\o one ori;;in; that distri- 

 bution over the eaitli is due to physical causes; that 

 the oritrin of the ninth temperate flora is ciroumpolar. 

 One who is iinfamiliar with the points of view of his 

 time ( .iiinot I- iti h the lul! sii;niflcaiici' of these conclu- 

 sion 1 I . I ' II ]ited, not challenged. Into 

 ]iiiii I I I i-ultivated plants he made 

 ii Ills paper on the running 



casional contributii 



ithi 



Asa Gray was a lovable man. He was gentle, quiet, 

 sweet-tempered; intellectually he was keen and pene- 

 trating. Both by his personality and his teaching, he 

 exerted an incalculable influence on American botany, 

 and, indeed, on American biological science. In Europe 

 he became a representative of what was best in Ameri- 

 can s.-ii lice. Harvard College, in which he held a pro- 

 f.s,,,. -I;;;, 1 1 .,,1 1 ~ (2 until his death, became the Mecca of 



e', li-iaiiist. Here he built up the most 



ii;i;" li, ' : ;,'iiiiii and botanical library in the New 



\\ I.J li. No v :i< I iie master of American botany. 



liray s writings were voluminous. He was known as 

 oiiB of the most skilful of American reviewers and bi- 

 ographers. His scattered untechnical writings were 

 republished in two volumes in 1889, by Professor Sar- 

 gent, as the "Scientific Papers of Asa Gray." See the 

 " Letters of Asa Gray," 2 vols., 1893, by his widow, Jane 

 Loring Gray. L. h. B. 



GREENHOUSE. In America the word Greenhouse is 

 used generically for any glass building in whicli plants 

 lire grown, with the exception of coldframes and hot- 

 beds. Originally and etyraologically, however, it means a 

 house in which plants are kept alive or green: in the 

 Greenhouse plants are placed for winter protection, and 

 it is not expected that they shall grow. The evolution 

 of the true Greenhouse seems to have begun witli the 



an dv 



mg 



dows were inserted; and later, a glass roof was added. 

 In early times it was thought best to have living rooms 

 above the Greenhouse, that it might not freeze tli rough 

 tlie roof. Even as late as 1806, Bernard McMahon, 

 writing in I'hiladelphia, felt called upon to combat this 

 idea. The old or original conception of a Greenhouse as 

 a place for protecting and storing plants is practically 

 extinct, at least in America (Fig. 980). 



Other types of plant houses are the conservatory 

 (which see), in which plants are kept for display; the 

 forcing-house (see Forcing), in which plants tire forced 

 to grow at other times than their normal season ; the 

 stove or warrahouse ; the propagating pit. Originally 

 the warmest part of the plant-house, that part in which 

 tropical plants were grown, was heated by a stove made 

 of brick, and the house itself came to be called a stove. 

 This use of the word stove to designate the warmest 

 part or room of the range is universal in Engl.aml, but 

 in America we prefer the word warnilnmse land this 

 word is used in this Cyclopedia). Originally, hotiiouse 

 was practically equivalent to stove, but tiiis term is 



GREENHOUSE 685 



little used in this country, and when used it is mostly 

 applied generically in the sense of Greenhouse. 



It will thus be seen that there is no one word which 

 is properly generic for all glass plant houses. The word 

 glasshouse has been suggested, and it is often used in 

 this work; but there are other glass houses than those 

 used for plants. It seems best, therefore, to use the 

 word Greenhouse for all glass buildings in which plants 

 are grown; and usage favors this conclusion. 



The long, low (greenhouse range, of the type which 

 we now know in our commercial establishments, 

 probably had a different origin from the high-sided 

 Greenhouse. The glasshouse range appears to have de- 

 veloped from the practice of protecting fruits and other 



plants against a wall. In European countries, particu- 

 larly in England, it is the practice to train fruits and 

 other plants on stone or brick walls, in order that they 

 may be protected from inclement weather and receive 

 the greater sun heat which is stored up in the masonry. 

 It occurred to Nicholas Facio Duilhier to incline these 

 fruit walls to tlie horizon so that tb.-v would receive the 

 greater part ot tin- im i-ii t,t i.ii - i i ihe sun at right 



angles. He wn.ie a 1 w . .. ■ ■■ i,:i . i of "Fruit-Walls 



Improved," whii-li «;is i . . ! m Ini^land in 1099. 



Facio was a iiKiilninati : .11. :,;,il In worked out the 

 principle of the inclined walls from mathematical con- 

 siderations. Sucli walls were actually built, but accord- 

 ing to the testimony of Stephen Switzer, who wrote in 

 1724, these walls were not more successful than those 

 which stood perpendicularly. Certain of these walls on 

 the grounds of Belvoir Castle, and over which grapes 

 were growing, received the additional protection of 

 glass sash set in front of the inclined walls and over 

 the vines. In n.Mifio,, to ti.!^, tines y,e,-e constructed 



behind the wall ;■; ..".1. y ■■•:,• I., .n i.- ■! : I ,. m. Tho 



construction ot n ii:...niinon 



in that day. TI. :■;■ i. ' :. i- ■■'■ ' : I. loilowed 



this experiment iniiii.'.-l Si, ii . n- 1.. ili. |._-ii l' 1.. - -i-overed 

 walls. The "glasshouse" which he pictured in the 

 "Practical Fruit-Gardener" (1731) represents a Green- 

 house 3K ft. wide in the clear, Fig. 987. At the back of 

 this house is an inclined heated wall on which the 

 grapes are grown. Three and one-half ft. in front of 

 this, a framework is erected to receive the sash. There 

 are 3 tiers of openings or windows along the front, the 

 two lower ones of which are for wimlow sash, and the 

 upper ono is vacant in order to proviile for ventilation 

 and to allow space to receive the lower sash when they 

 are lifted up. The whole structure is covered with a 

 roof or coping. Switzer declares that the introduction 

 of these covered, sloping walls "led the world" to the 

 "Improvement of glassing and forcing grapes, which 

 was never done to that Perfection in any Place as it is 

 vated and 

 his 



"History of English Gardening," quotes the remarks of 

 Switzer, and makes the statement that the use of these 

 walls"Ied to the first erection of aregular forcing struc- 

 ture of which we have an account." The immediate out- 

 come of these covered walls seems to have been the 

 lean-to Greenhouse, and from that has developed the 

 double-span glass range of the present day. Long be- 

 fore Switzer's time plants were forced in a crude way, 

 even by the Romans, mostly by being placed in baskets 

 or other movable receptacles, so that they could be 

 placed under cover in inclement weather; but the im- 

 provements of Facio and Switzer seem to have been 



