J0LT 2, 1915] 



SCIENCE 



33 



The scope of the undertaking may be under- 

 stood when one considers that nearly 50,000 

 references are brought together. These have 

 been gathered from all sources, notably from 

 all accessible bibliographies, serial publica- 

 tions and book catalogues. Finally, the effort 

 was made to complete the lists of titles by 

 bibliographies secured in so far as possible 

 from authors themselves. To this end circulars 

 were sent out to several hundred vsriters on 

 ichthyology, many of whom responded cor- 

 dially. 



There still remain, however, a number of 

 individual writers who have not contributed 

 the titles of their publications. I have, ac- 

 cordingly, been led to publish the present note 

 in the hope that any who have not already sent 

 to Dr. Eastman or myseK their bibliographies 

 may be reminded that we are especially anxi- 

 ous to make the work as complete as possible. 

 And we urge that their lists be sent in without 

 delay, for the work is undergoing its final re- 

 vision and the first volume is shortly to go to 

 press. This is the " author's " volume which 

 wiU consist of about 1,000 pages and include 

 under the names of writers a serial list of 

 their publications. The second, or " subject " 

 volume, will be a classified index of the titles 

 in volume I. Here one has access to special 

 papers in the various branches, for example, 

 in anatomy, distribution, embryology. 



Bashford Dean 



American Museum of Natural History, 

 New York 



SPECIAL ASTICLES 



THE ACTION OF POTASSIUM CYANIDE WHEN INTEO- 

 DUCED INTO TISSUES OF A PLANT 



In an issue of Science last autumn'- Pro- 

 fessor Sanford mentioned some experiments 

 conducted in California in destroying the 

 Australian bug, Icerya purchasi, by the use of 

 potassium cyanide placed in the tissues of the 

 tree. Since that issue, a number of articles or 

 notes have appeared from time to time dis- 

 cussing the possibility of the use of potassium 

 •cyanide for the destruction of various sucking 

 ■and wood-boring insects, but no experimental 



1 Vol. XL., No. 1032, page 519. 



evidence was given as to how the cyanide acted 

 in the tree or why it should kiU the insects. 

 During the winter and spring, a few experi- 

 ments were conducted along these lines. The 

 first work was done on geraniums. A hole 

 was made near the base of the plant and a 

 small piece of potassium cyanide, about half 

 the size of a pea, was placed in the stem. A 

 split piece of rubber tubing was placed around 

 the stem and sealed tight with paraffin to pre- 

 vent leakage. Twenty-four hours later the 

 plant was examined for the presence of cya- 

 nide. The potassium cyanide had disappeared, 

 but the odor of cyanide was present at the 

 wound. Sections of the stem were cut longi- 

 tudinally and crosswise and tested by the 

 Prussian blue reaction. Thick sections were 

 placed in a 5 per cent, solution of caustic 

 potash for about a minute, then transferred to 

 a solution containing 2J per cent, of ferrous 

 sulfate and 1 per cent, of ferric chloride, heated 

 to 60° C. After ten minutes, they were placed 

 in a mixture of one part hydrochloric acid to 

 six parts water. When cyanide was present, 

 the sections showed the Prussian blue re- 

 action in from ten to fifteen minutes. 



Prom Mr. Sanford's article, one would ex- 

 pect the reaction to show in the vascular 

 bundles or in the water-conducting tissue of 

 the plant. Such, however, was not the case. 

 Cyanide showed only in the outer cortical 

 layer and in the inner pith cells, the strongest, 

 however, in the cortical layer. The lignified 

 tissue gave no reaction. Positive tests could 

 be obtained for a distance of about one foot 

 above the wound, but only about an inch or an 

 inch and a half below the wound. 



Other treated plants were allowed to con- 

 tinue for several days, to study the effects on 

 the plant. It was noticed that whenever the 

 cyanide reached the axle of a leaf, the petiole 

 withered and died within a half-inch of the 

 base, the leaf hanging down from the plant. 

 Similar results were obtained whenever the 

 cyanide reached a succulent offshoot, the cy- 

 anide seeming to blister the tissue. Tests for 

 cyanide could not be obtained beyond the 

 injured portion which was at the point of at- 

 tachment to the stem. The reaction at that 



