December 20, 1912] 



SCIENCE 



875 



is that birds, if they feed on insects to the ex- 

 tent shown in this instance, must play a much 

 more important part as checks on the num- 

 bers of insects than many people have hitherto 

 believed. 



Stomach examination has shown that a con- 

 siderable percentage of the food of the west- 

 ern meadowlark is made up of ground beetles, 

 these insects being eaten every month of the 

 year. The harm done in destroying beetles 

 considered beneficial because of their preda- 

 cious habits (e. g., Oalosoma) is in a large 

 measure counteracted by the destruction of 

 certain injurious elaterid (e. g., D. rasterius) 

 and chrysomelid (e. g., Diabrotica soror) 

 beetles. The stomach of a meadowlark taken 

 at Big Pine, Inyo County, California, No- 

 vember 20, 1911, contained over thirty-six 

 chrysomelid beetles of the species Diabrotica 

 soror. In that this species is very destructive 

 in the state, and as insecticides are seldom 

 used as a means of control, any natural 

 means of cheek becomes of importance, and 

 should be so recognized. 



A knowledge of the part played by certain 

 birds in the economy of nature is yearly be- 

 coming more important and demands atten- 

 tion, lest the information needed be forth- 

 coming too late. As the fairest test of the 

 value of a bird is dependent on a knowledge 

 of its food habits, the investigation in hand 

 will help to demonstrate the economic value 

 of those birds now considered of doubtful 

 value. The investigation will not stop with 

 a knowledge of the food habits alone, for the 

 life history of each bird and its relation to its 

 environment constitute factors almost as im- 

 portant, which must be considered. The 

 justification of the investigation does not 

 only lie in the increased information as to 

 the food of birds, but in the saner protection 

 which must necessarily follow the knowledge 

 of the use of birds. 



Harold C. Bryant, 

 Assistant, California State Fish 

 and Game Commission 



Zoological Laboratory, 

 University of California, 

 Berkeley, California 



THE MOSAIC DISEASE OF TOBACCO 



During the past winter an investigation of 

 the Mosaic disease of tobacco was undertaken 

 by the writer. Mosaic has been generally 

 regarded as a so-called physiological disease 

 and it was planned to carry out the investiga- 

 tion along physiological lines. However, cer- 

 tain observations soon brought to light new 

 facts which would seem to throw considerable 

 doubt on former views as to the nature of the 

 malady. It was found that insects are in- 

 volved in the dissemination of the disease and 

 the Bureau of Entomology has undertaken to 

 follow up this phase of the problem. It will 

 doubtless require considerable time to work 

 out satisfactorily the questions involved, but 

 it is thought desirable to announce the more 

 important facts which have been established 

 regarding this obscure disease. 



Susceptibility of other Solanaceous Plants 

 to the Mosaic Disease 



Heretofore, no investigator has shown defi- 

 nitely that the mosaic disease of tobacco is 

 co m municable to other plants. The writer, 

 however, has readily transferred the disease 

 from tobacco to a great variety of solanaceous 

 plants. By inoculation the disease has been 

 obtained in plants of the following genera: 

 Nicotiana, Lycopersicon, Petunia, Physalis, 

 Datura, Hyoscyamus, Solanum and Capsicum. 

 A mosaic plant of the species (Solanum caro- 

 linense) brought to the writer's attention, in- 

 dicates that the mosaic disease of tobacco 

 sometimes occurs in strictly wild plants. 



Efforts to inoculate the common potato 

 (Solanum tuberosum) , the eggplant (Solanum 

 melongena) and belladonna (Atropa bella- 

 donna) were without success. Among the 

 species of Nicotiana, it has not yet been pos- 

 sible to develop the disease in the species 

 N. glauca and N. viscosum. 



Appearance of the Blossoms of Mosaic 



Tobacco Plants 

 The development of mosaic in all varieties 

 of Nicotiana tabacum usually affects the in- 



