October 25, 1907] 



SCIENCE 



543 



one-sided. The brain of the pathologist is 

 his most important instrument in such 

 investigations. It must be trained to 

 work with precision in all of the various 

 directions and fields involved in such study. 

 This is not now generally the case, and our 

 colleges must be awakened to their duty. 

 To most successfully combat a disease, we 

 should know the causes that . contribute to 

 it and as much about the causes as possible. 

 We should understand the pathological re- 

 action of the diseased plant. Only in this 

 way shall we be able to remove the causes 

 or protect the plant against them or assist 

 it to recover. 



SPRAYING 



In the cases of disease due to attack of 

 parasitic organisms, we are often able to 

 protect our crops by spraying. Spraying, 

 like a coat of mail, is a protection against 

 entrance to the tissues by invading organ- 

 isms. If there are any holes in the coat of 

 mail or if it is made of poor material or 

 is put on after the arrow has pierced the 

 flesh, it may be of no avail. Much of our 

 spraying has holes in it. The tissues are 

 not properly coated during the periods of 

 attack. Much of the new growth is left 

 unprotected during the critical period. 

 The parasite gets in through these places, 

 and we find too late that hasty, careless 

 spraying is of little value. 



Improperly made mixtures, or mixtures 

 made of poor materials, are often of no 

 protection and may be as injurious as the 

 disease. Even good Bordeaux mixture can 

 not safely be used on some plants, like 

 peaches, and in some seasons is slightly 

 injurious to apples. 



The apparatus for spraying is, as a rule, 

 poorly constructed, clumsy and in great 

 need of general improvement and adapta- 

 tion to particular conditions. Demand 

 good machinery and pay for it. It is 

 essential to success. Those who know these 

 things must teach, hy demonstration, those 



who know imperfectly or do not know at 

 all. Literature is valuable as an aid to 

 demonstration teaching, but can never take 

 the place of it. Too much dependence on 

 literature is one of our great educational 

 mistakes. Send out fewer bulletins and 

 more men. 



Briefly, then, we shall improve on the 

 pathology of the last century if we take 

 time to be careful and thorough; study 

 the causes of failure and profit by the re- 

 sults ; demand better-trained minds and 

 improved apparatus, ' and depend in our 

 teaching more upon men and less upon 

 books. A. F. Woods 



Bureau of Plant Industry, 



U. S. Department of Agriculture 



SCIENTIFIC BOOKS 

 The Carboniferous of the Appalachian Basin. 



By John J. Stevenson, Professor of Geology 



in New York University. Pp. 595. 



This is the title of a volume recently issued 

 by Judd & Detweilei*, of Washington, D. C. 

 The volume consists of four papers previously 

 published in the Bulletin of the Geological 

 Society of America between 1903 and 1907. 



The subjects treated in these several papers 

 in order of publication are : " Lower Carbon- 

 iferous," a paper of 82 pages, presented before 

 the society, July 1, 1902, and published March 

 28, 1903; "The Pottsville " is next discussed 

 in a paper of 174 pages, presented before the 

 society, January 1, 1904, and published under 

 date of May 28 of the same year; the "Alle- 

 gheny " and " Conemaugh " formations were 

 discussed in the third paper of 165 pages, 

 presented before the society, December 29, 

 1905, and published May 28, 1906, while the 

 concluding paper of 174 pages, including an 

 elaborate index, presented before the society 

 December 29, 1906, and published under date 

 of April 19, 1907, deals with the " Monon- 

 gabela " and " Dunkard " formations, ending 

 with a chapter on " Geographical Changes 

 during Pennsylvanian " time, and some 

 " Paleontologic Notes " upon the fauna and 

 flora of the Pennsylvanian. 



