216 



SCIENCE 



[N. S. Vol. XLIII. No. 1102 



ments miglit be made to advantage; for in- 

 stance, ice storms should be associated with 

 sleet instead of with dew and frost ; and perco- 

 lation perhaps belongs with the relations of 

 precipitation and vegetation to water supply 

 and stream flow, rather than to the section of 

 atmospheric precipitation. This classification 

 is less complete, but more easily remembered 

 than the International; and, being more re- 

 cent than either the International or the Dewey 

 systems, it meets in a satisfactory way the 

 general requirements of modern meteorolog- 

 ical literature. 



Mr. Robert Seyboth has compiled a valu- 

 able list of the " Serial ISTumbers of Weather 

 Bureau Publications." ^^ The numbers begin 

 with 60 in 1895 and end with 560, the Monthly 

 Weather Review for July, 1915. The list em- 

 braces the vast majority of "Weather Bureau 

 publications, and, in addition, the important 

 imnumbered publications are mentioned. 



Professor A. J. Herbertson died July 30, 

 1915, at the age of 50 years. He is noted in 

 meteorology particularly for his contribution, 

 " The Distribution of Eainf all Over the Land," 

 compiled for the Eoyal Geographical Society 

 in 1900, and for his editorship of the Oxford 

 Wall Maps. 



Mr. Walter G. Davis, director of the Oficina 

 Meteorologica Argentina for more than 30 

 years, has retired on a pension. Mr. George 

 Wiggin, a native of New Hampshire, for 21 

 years assistant director, is now acting director. 

 Charles F. Brooks 



Tale Univbksitt, 

 January 3, 1915 



SPECIAL ARTICLES 



THE DEVELOPMENT OF THE PHYLLOXERA 

 VASATRIX LEAF GALL 



In Bulletin 209, recently issued by the 

 United States Department of Agriculture, en- 

 titled " Testing Grape Varieties in the Vini- 

 fera Regions of the United States," Husmann 

 makes the following statements, p. 12 : 



The number of swellings, nodosities and tuberos- 

 ities from insect punctures and the rotting of 



11 Mo. Weather Bev., July, 1915, pp. 346-350. 



the root occasioned by them progress more or less 

 rapidly and deeply in accordance with the texture 

 and character of the root attacked. The weaken- 

 ing and ultimate death of the vine are determined 

 by the extent of the punctures and the progress 

 of the rot upon the roots. 



Although Cook suggested that puncturing 

 may be the stimulus for the gall production 

 occasioned by the aphids, no evidence has ever 

 been presented to confirm this theory. To the 

 contrary, after intensive study of the grape- 

 vine leaf gall produced by this insect, the 

 writer has gathered evidence showing that so 

 little puncturing is done by the insect that, as 

 a gall-producing stimulus traumatic punctur- 

 ing may be regarded as playing a very minor 

 part. Histological sections of leaves attacked 

 by Phylloxera readily reveal the actual punc- 

 turing done by the insect. This manifests it- 

 self in the broken-up condition of the epi- 

 dermal and mesophyll cells through which the 

 proboscis has passed. In a considerable num- 

 ber of slides, microscopic examination shows 

 the proboscis itself passing through the punc- 

 tured and broken-up cells. The writer has 

 never found more than two or three epidermal 

 cells and as many mesophyll cells thus rup- 

 tured. So slight a disturbance can not be 

 looked upon as the main cause of such large 

 hyperplastic growths as are produced on the 

 leaves of the vine or on the roots of the vine. 

 This view is substantiated by Cornu's excel- 

 lent work upon the root swellings induced by 

 the attacks of this insect. 



The one thing that is definitely certain 

 about the work of Phylloxera is the fact that 

 it obtains its food by means of a sucking 

 action. This action usually continues for 

 about 12 to 15 days at one particular point on 

 the leaf, and around this point, which may be 

 called the sucking center, the gall develops. 

 During this time the insect has obtained 

 enough food to enable it to sustain itseK, to 

 increase its bulk considerably, and to produce 

 several hundred eggs. The withdrawal of so 

 much food at one point from tender growing 

 leaves, the subsequent changes in tension and 

 pressure at this point, and certain structural 

 peculiarities of the gall itself, all suggest the 



