23 



suited to tlie production of tlie best grades of sberry, and tlie annual 

 output of tliis expensive wine is only 35,000 butts.* Adjoining districts 

 produce wine whicb, although, sold as sherry, is of a quite inferior 

 quality. The Avell-known Eheingau region of the Ehine, producing 

 some of the most famous varieties of wine, such as the Steinberger 

 Zeltinger, Assmanshausen, and others, is extremely limited in extent, 

 and depends in large part, according to recent investigations by Mr. 

 W. T. Swingle, upon the i)resence in that region of a particular kind of 

 clay shale {TJionschiefer). The same varieties of Kiesliug grape grown 

 in France upon other soils fail to produce comparably excellent wines. 



The suitabihty of the region about Cannes and Grasse, France, to 

 the growth of roses and other perfume-bearing plants has led to the 

 building of extensive perfame factories there. The fruitless attempts 

 to reproduce the Yuelta Abaja tobacco or the Sumatra wTapper in 

 regions other than those in which they have earned their celebrity all 

 point to the presence of certain soil and climatic conditions to which 

 the plant varieties are x^articularly susceptible, but which are as yet 

 not perfectly understood. 



As pointed out by Dr. Merriam in his recent bulletin on Life Zones 

 and Crop Zones of the United States,! the problem of plant introduc- 

 tion is inseparably associated with a mapping of the crop areas of the 

 United States and a study of the conditions for plant growth leading 

 to the discovery of regions suited to the cultivation of certain crops. 

 Such preliminary studies of the laws of temperature which control the 

 geographic distribution of cultivated plants will be found of great 

 value in a general way, but there are so many influencing factors, such 

 as early or late blooming, time of harvest, possibility of artificial pro- 

 tection from extremes of temperature, or relation to the conditions of 

 the nearest market, that the narrow limits of successful culture of a 

 definite crop will only be ascertained by actual trial. 



The problem of distributing an annual crop is in many resx)ects dis- 

 tinct from that connected with the establishment of perennial plants, 

 since the factor of permanence does not play so important a part. On 

 the other hand, the rapid deterioration brought about by the crossing 

 of valuable varieties with inferior sorts leads frequently to a loss of 

 newly imported kinds in the course of a few years, making it impera- 

 tive that at least a part of the seed imported be placed in the hands of 

 experts acquainted with the processes of crossing and seed selection. 



The necessity of a permanent label for a newly introduced tree or 

 shrub whose varietal characteristics only appear after several years 

 is readily, appreciated, since any confusion in the nomenclature of in- 

 troduced plants is an evil which might easily entail in the course of 

 years immense and often irretrievable losses. It too often happens that 



*Cliapman, Abel, and Buck; Walter J. Wild Spain. London^ 1893, Gurney and 

 Jaclcsou. 



t Merriam, C. Hart. Life Zones and Crop Zones of the United States. Bull. No. 

 10, Division of Biological Survey, U. S. Dept. of Agriculture, 1898. 



