60 DEPARTMENTAL REPORTS. 



son's work, and these should produce at least two or three thousand 

 seedlings, from which we hope to obtain pears having the quality of 

 the Bartlett and Seckel and the disease resistance of the Kieffer. Sev- 

 eral hundred fine seedling hybrids are now growing on the Department 

 grounds as a result of our work in this line. We hope to continue the 

 work each year until an entirely new race of pears, which will cover 

 all seasons of the year, is obtained. Similar work will also be carried 

 on with the apple. As stated under "Diseases of fruit," some peaches 

 seem immune from rot in orchards where the disease is very destruc- 

 tive. It is hoped to undertake experiments in breeding varieties 

 which will resist this disease. 



Pineapples. — A number of pineapple hybrids produced by crossing 

 and now growing in Florida have fruited this year for the first time. 

 The proportion of valuable hybrids in this collection is remarkable, and 

 the fruit is excellent. The extent of variation shown is remarkable, no 

 two being alike. The production of smooth-leaved varieties was one 

 of the main objects of the crossing, and some of the best of the hybrids 

 have smooth leaves. The valuable hybrids will be propagated a, 

 rapidly as possible and tested more thoroughly, but it will require 

 several years to secure sufficient stock to enable us to distribute plants 

 to growers. A number of the hybrids have not yet fruited and it is 

 probable that other valuable sorts may be secured from these. As the 

 pineapple is one of the most important fruits in our new possessions 

 and its commercial importance to Florida is second only to the orange, 

 the production of improved varieties is of considerable moment, and 

 work with it will be extended and vigorously prosecuted. 



Miscellaneous fruits. — Some work has been started on other fruit 

 crops which are not of so great importance commercially. In the case 

 of the guava, which is one of the most important household fruits of 

 the Tropics and subtropics, many selections have been made of plants 

 producing very few seeds. A number of seedlings of these are being 

 grown, with the hope of securing varieties with fewer seeds than any 

 now known. The guava is capable of great development and should 

 be carefully bred. Work is also being carried on with the strawberry 

 in the hope of producing late varieties, and this will be continued 

 the coming season. 



Principles of breeding. — In connection with the practical work in 

 progress, a careful scientific study is being made of the principles 

 underlying breeding. While many fundamental principles are well 

 understood, some of them are still quite obscure, as, for instance, 

 the effect of environment on plants, which is so important and the 

 knowledge of which is so meager that it can not be intelligently util- 

 ized. Experiments for the purpose of obtaining light on this factor 

 have been arranged with several of the experiment stations. The pre- 

 potency of pollen and preponderance of one species over another in 

 hybridization are not understood with any degree of accuracy and are 

 being investigated. The immediate effect of pollen, until recently a 

 botanical enigma, has finally been cleared up and is now thoroughly 

 understood, the work which we have carried on having had much to 

 do with its final solution. The problems of heredity, which are among 

 the most obscure and important of biological questions with which the 

 scientist has to deal, bear closely on the work of the practical breeder, 

 and studies looking to a clearer understanding of the laws governing 

 these will be prosecuted as rapidly as possible. 



