391 



Apatela tritona Hiibner. 



Mature larva. — The head is of a purplish color, darker on the vertex, -^ith a lat- 

 eral line. The body is light yellowish green, with a purple brown dorsal stripe bor- 

 dered with reddish yellow, interrupted on joint 6 and inclosing a reddish green patch 

 on joints 8 to 11. The spiracles are black ; the hairs long and black, few in number. 



Food plants, species of Vacciniiun. Larva? from Ulster County, New York. 



EXTRACTS FROM CORRESPONDENCE. 



The Quicksilver Remedy for Phylloxera. 



The Scientific American paper, of this city, published the 10th of June, 18>^5, that 

 Mr. John A. Bauer, of San Francisco, California, had found a sure and cheap pre- 

 ventive of the ravages of the "Phylloxera," which consisted in the application to 

 the vine plant of a compound of half on ounce of quicksilver in very minute i)arti- 

 cles and an equal weight of x^ulverized clay. The quantity of the mixture had to be 

 half an ounce for each plant. The journal added that the remedy was simple ; that 

 it could be prepared, assayed for several purposes, and applied without danger or 

 technical skill. 



I consequently wrote to my friends, Mr. John B. Pratt and Mr. Paul Griiian, of Bar- 

 celona (Spain), on the subject, and I invited them to give a trial to the important 

 discovery of Mr. Bauer. Mr. Pratt wrote to me subsequently as follows : 



*' I have the regret to inform you that our friend, Dr. Grinan, has tried for one hun- 

 dred times at least to prepare the anti-phylloxera compound discovered by Mr. 

 Bauer in San Francisco. He (Mr. Grinan) has used all the means that science and 

 experience advise, but to no avail, because he has not been able to obtain the assimi- 

 lation of the mercury and the clay. There must therefore exist either an especial ma- 

 chine or an ingredient unknown so far to us for making the anti-phylloxera prepara- 

 tion, and we earnestly beg of you to inquire about the matter and inform us." 



I consequently wrote to Mr. Bauer on the 3d of last March, but as yet have received 

 DO answer. A friend of mine, Mr. MacArdle, who knows you by your high reputation 

 as the best judge in the phylloxera question, has advised me to take the liberty of 

 consulting you on the matter, and it is for this reason that I come to beg of your 

 extreme kindness the favor of informing me how can my friend in Barcelona succeed in 

 making the compound invented by the above-mentioned Mr. Bauer. * * * — [Joseph 

 de Susini, 103 West Fourteenth street. New York, X. Y., April 7, 1991. 



Reply. — I have your letter of the 7th of April, referring to Bauer's quicksilver 

 remedy for grapevine phylloxera. This remedy was proposed in 1884 and attracted 

 considerable attention at that time. So far as I am aware, Mr. Bauer has not pub- 

 lished his method of mixing the earth and the mercury. In Bulletin No. 18 of the 

 Agricultural Experiment Station of the University of California, published October 1, 

 1884, Prof. E. W. Hilgard, in treating of this remedy, says there can be no doubt as 

 to the efficacy of metallic mercury finely diffused through the soil in killing phyl- 

 loxera or any other small insect remaining within its reach for any length of time. 

 In another paragraph of the same bulletin he makes use of this expression : '-A soil 

 column of 6 or 8 inches depth, impregnated with the mercurial vapor by intermix- 

 ture with ' blue mass,' will effectually prevent, etc." In other words, the mixture if, 

 spoken of as a simple mechanical operation, and I was not hitherto aware that there 

 was any difficulty with that phase of the application. I was not at all favorably im- 

 pressed with the remedy at the start, and the experiments made later by Professor 

 Hilgard and his assistants failed in a large majority of cases to produce the expected 

 effect. Mr. Bauer's original idea was to i^lace a small quantity of the mixture about 

 the base of the vine, to prevent the underground forms from crawling up, the vapor 



