538 



SCIENCE. 



[X. S. Vol. XVIU. No. 4(i0. 



where there was the slightest ahrasion of the 

 epidermis, produced by a fine needle, gave char- 

 acteristic spots filled with bacteria in from 

 forty-eight to seventy-two hours. Charac- 

 teristic spots have also been secured by simply 

 brushing the bacteria on the uninjured 

 leaves. Under natural conditions the bacteria 

 appear to gain entrance to the leaves and stems 

 from the slight injuries produced by the red 

 spider and by other causes. Slugs have been 

 observed eating diseased spots, and infection 

 from slug bites was observed. It is also evi- 

 dent that the organism has other ways of gain- 

 ing entrance to the tissues, possibly through 

 the stomata. We have found the disease so far 

 on the varieties Mrs. McKinley, Mrs. Nelson, 

 Lawson, and Crane, and it will doubtless be 

 found on numerous other varieties. In some 

 cases observed nearly every leaf and many of 

 the stems were so badly spotted that it would 

 be practically impossible to save the plants. 

 When the disease has not progressed so far, 

 however, it can be checked by thoroughly 

 cleaning the plants 6f all diseased leaves and 

 stems and burning what is removed. Then 

 syringe the plants with a solution of com- 

 mercial formaldehyde, one part to five hundred 

 parts of water. This should be done in the 

 forenoon so that the plants may dry before 

 night. Syringe occasionally with water under 

 pressure to keep down the red spider. Give 

 the plants as much light and air as possible 

 and keep the foliage as dry as practicable. 

 Give the plants a second thorough cleaning 

 after the new growth is well started and fol- 

 low with a second light syringing with formal- 

 dehyde solution. It is probable that these 

 recommendations may be modified after fur- 

 ther investigation, but the procedure outlined 

 is the best we can suggest at the present time. 



A careful study of the disease and the 

 organism causing it will be completed as soon 

 as possible. Messrs. Lloyd Tenny and J. B. 

 Eorer, assistants in pathology, are actively 

 aiding in the investigation. 



A. F. Woods, 

 Pathologist and Physiologist. 



U. S. Department op Agricdltube. 



THE frontier OF PHYSIOGRAPHY. 



The term physiography, as generally ap- 

 plied in geological studies, has become asso- 

 ciated with and is inclusive of glacial geology ; 

 and from the character of the formations 

 studied is sometimes referred to as superficial 

 or surficial geology. The alternative use of 

 the latter terms calls attention, also, to the 

 fact that the field of its inquiries has not been 

 generally regarded as extending deep into the 

 earth's crust. As time has gone on the work 

 of physiography has, in fact, been more and 

 more sharply differentiated from that upon 

 the consolidated portion of the lithosphere; 

 and geologists of a special class have arisen 

 knovni as physiographers, glacialists or sur- 

 ficial geologists — which, while not by any 

 means equivalent terms, are yet regarded as 

 all properly referring to men trained in a 

 special way. 



The features of the land areas are by this 

 school of geologists interpreted to be largely 

 fashioned under the action of water or ice, 

 or both ; in the case of the first of the agencies 

 mentioned, according as the action has been 

 affected by epeirogenic movements. The ori- 

 gin of earth sculpture has been, therefore, 

 largely referred to the changes brought about 

 by successive geographic cycles, during which 

 elevation and tilting of the crust follow upon 

 a period of subsidence. In a subordinate 

 degree the relative hardness of the underlying 

 rocks is brought into account by the modern 

 school. As a result of this type of specializa- 

 tion or special generalization stress has been 

 laid upon the general contours which are char- 

 acteristic of a district or province, and with 

 remarkable readiness and accuracy the stage 

 of a geographic cycle through which a prov- 

 ince is passing, and many of the earlier events 

 of the cycle as well, are determined. 



The unconsolidated deposits in glaciated 

 regions have been further studied with minute- 

 ness as regards their form and extent as well 

 as their composition, and an elaborate classifi^ 

 cation of them has been adopted. To the 

 consolidated or ' hard ' rocks this study has 

 not, however, been extended; and, beyond the 

 fixing of what may be termed erosional ear 

 marks to determine the agent and the stage 



