176 POPULAR SCIENCE MONTHLY. 



purposes and usefulness of these institutions have steadily broad- 

 ened until all the more important phases of the subject are more 

 or less represented in the greater majority of instances. 



In addition to the scientific and practical uses enumerated 

 above, the botanic garden has become a laboratory for the land- 

 scape artist, who may dispose of its masses of plants with a feel- 

 ing regard for their artistic value in outline and color, making a 

 most effective means of cultivation and gratification of public 

 taste. In many of the better known gardens, especially those 

 located in the great cities, this aesthetic feature has become a very 

 prominent and in manj'' instances the predominant idea. 



Only when a botanic garden is equipped with laboratories for 

 the furtherance of investigation, and sustains an organic relation 

 to a school or university, may it be said to attain its highest pos- 

 sibilities of usefulness, in the demonstration of the principles 

 governing the nature and development of one of the two great 

 groups of living things. When designed for this purpose the 

 collection of growing plants should represent as many of the prin- 

 cipal forms of vegetation as is possible. Since the probable num- 

 ber of living plants is estimated at half a million, it is obviously 

 impossible to bring together in any restricted area more than a 

 fraction of this number. A census of the flora of the section of 

 Bronx Park in New York, inclusive of about two hundred and 

 fifty acres, which is to be converted into a botanic garden, showed 

 that nearly a thousand species of ferns and seed-forming plants 

 were to be found on that area, only a small number of which were 

 introduced. Of these thousand species many were represented by 

 thousands or perhaps hundreds of thousands of individuals. In 

 the conversion of the tract into a botanic garden, the gardener 

 will remove all but a few dozen, or perhaps a few hundreds, of 

 each species, which will be confined to certain designated limited 

 areas. In this way he will relieve each species from the compe- 

 tition of its neighbors, and so far as possible from the ravages of 

 insects and animals the most telling factors in the struggle for 

 existence and obtain space for the introduction of a large num- 

 ber of species. If these conditions alone determined the flora of 

 a region, the number of species which could be grown in a garden 

 would be determined only by its size and the number of plots it 

 might contain. It is found, however, that the substratum and 

 climate offer rigid limitations to an extension of the flora which 

 may be grown out of doors in any locality. The gardener par- 

 tially overcomes this limitation by the use of glass houses, where 

 plants from nearly all parts of the world may be grown in spe- 

 cially prepared soils, and kept at temperatures resembling those 

 of the natural habitats of the plants. But under such conditions 

 it becomes extremely difficult to properly adjust the moisture and 



