176 REPORTS Ot INVESTIGATIONS AND PROJECTS. 



published in 1879, comprised 684 pages. The volume for 1906 contains 

 1,596 pages. Transactions of societies are included under the above general 

 term of "periodicals." In addition to this steady increase there has been 

 added of late years a new and highly important series of reports from 

 laboratories devoted to research in biological sciences. The volume of the 

 Index Medicus for 1907 is being duly issued. 



Weeks, F. B. (under direction of Dr. G. F. Becker), U. S. Geological Sur- 

 vey, Washington, District of Columbia. Bibliography of geophysics. 

 Grant No. 423. (For previous reports see Year Book No. 3, p. 81 ; 

 Year Book No. 4, p. 86, and Year Book No. 5, pp. 90-91-) $1,200. 



Mr. Weeks reports that work upon this bibliography is practically com- 

 pleted and that author cards and index cards will be submitted to the Insti- 

 tution in a short time. 



BOTANY. 



Burbank, Luther, Santa Rosa, California. Grant No. 404. Experiments in 

 plant development. (For previous reports see Year Book No. 4, p. 

 125, and Year Book No. 5, p. 136.) $10,000. 



Within the limits of this annual report Mr. Burbank finds it possible to 

 give only a brief account of his experiments and operations in plant improve- 

 ment. This work, which has engaged his attention for the past 39 years, is 

 of steadily growing interest, and its cumulative results are more evident than 

 ever before- He has now under experimental test over 3,600 distinct species 

 of plants, and many thousand varieties of some of these. Over a million 

 seedling plants are raised each year for selection and for the study of varia- 

 tion from the effects of crossing. The newly developed fruit and fodder 

 plants are attracting great interest — not only in the United States, but in 

 many foreign countries. New species have been established which go on 

 their way with the same unchanging precision of typical characters as do any 

 of the species established in the past by nature. 



One of the interesting recent results is the production of a distinct new- 

 species of solanum (vS*. burbanki) by crossing 5*. guinense var., a native of 

 central West Africa, with S. villosum, of Chili. The experiments leading to 

 this new species were begun in 1895. From the cross-bred seeds numerous 

 plants were grown in the early part of the season of 1896, all practically 

 alike. Another generation of numerous individuals was brought into fruit 

 the latter part of 1896, this third generation embracing some 2,000 individ- 

 uals, all as much alike as if raised from any wild, fixed species. In 1907 

 the fourth and fifth generations have been produced, and among 30,000 

 plants, which have flowered and ripened abundantly, no variation toward 



