W) 



?SC1EHCE. 



PSYCHE. 



ORGAN OF THE CAMBRIDGE ENTOMOLOGICAL CLUB 



EDITED BY GEORGE DIMMOCK AND B. PICK.VIAN MANN. 



VoL II.] Cambridge, Mass., April, 1879. [No. 60. 



The Nervous System and Salivary Glands of 

 Phylloxera. 



I have read witli interest the remarks of Dr. E. L. Mark 

 upon this subject in Psyche for January. He is without doubt 

 right in his conclusion that what I have inadvertently called 

 nervous cords are, in reality, the tracheae ; I have been of this 

 opinion for some time. Dr. Mark's article suggests, however, 

 another thought which induces me to write these few lines. 

 M. Maxime Cornu has, under the direction of the French 

 Academy, made extended investigations into the nature of the 

 root swellings caused by Phylloxera vastatrix, arriving at the 

 conclusion, to me somewhat surprising, that they are purely the. 

 I'esult of the mechanical action of the puncture made by the. 

 insect, and of the subsequent absorption of liquids. These re^ 

 suits are recorded in an extended and elaborately illustrated; 

 memoir. 1 I have always believed Cornu's conclusions, essen- 

 tially erroneous, for the following reasons, which I quote from 

 mv 6th Report on the insects of Missouri, 1873, p. 70. 



" For a very minute and careful study of the pathological characteristics 

 of these swellings, the reader may refer to Maxime Cornu's excellent pa- 

 pers in the Comptes Rendu?, for 1873, and Memoires (xxii, no. 6) of the. 

 Academic des Sciences, Paris. He corroborates, by detailed observations, 

 the conclusions previously arrived at by Planchon and his followers ; but, 

 like too many of his countrymen, very generally ignores observations made 

 out of France, and consequently sometimes repeats as original, facts re- 

 corded elsewhere with less of detail. He concludes that the Phylloxera is 

 not nourished by the sap of the plant, but by plasmatic material which the 



1 Maxime Cornu. Etudes sur le Pliylloxera vastatrix. Paris, 1876, 



