800 



SCIENCE. 



[N. S. Vol. XXII. No. 572. 



rest of the organ reproduced itself. What 

 would seem to prove it is the fact that, as I 

 have said in speaking of No. 3, the dorsal fin 

 increased in size on account of the use he 

 made of it to replace the amputated caudal fin. 



A. DUGES. 



Guanajuato, INitExico, 

 April, 1905. 



LABORATORY EXPERIMENTS . WITH CS^ TO DETER- 

 MINE THE LEAST AMOUNT OF GAS AND THE 

 LEAST TIME REQUIRED TO KILL CERTAIN 

 INSECT REPRESENTATIVES OF VARIOUS 

 FAMILIES.^ 



While a sufficiently large series of insects 

 has not yet been worked upon to draw a defi- 

 nite conclusion upon the above point, the fol- 

 lowing paper is submitted as showing some 

 interesting results incident to this work. Ex- 

 periments were begun in California a few 

 years ago, and continued for a time in Minne- 

 sota. Three hundred and eighty-six insects 

 have been tested. Of this number some have 

 not been included in the tables, where the 

 record was not regarded as sufiiciently com- 

 plete. 



The points which might be brought out by 

 an exhaustive series of observations in this 

 line are as follows : Least strength required 

 with a minimum expenditure of time to kill 

 (a) insects in general, (h) particular groups, 

 safety to foliage being understood; effect of 

 moisture upon results; effect of temperature 

 upon results ; expense of material for effective 

 use upon a known number of plants, trees, 

 insect colonies or stored products, what per 

 cent., if any, succumbed after seeming recov- 

 ery; beginning effects of gas upon (a) insects 

 in general, (b) groups in particular; signifi- 

 cance of occasional spasmodic movements of 

 legs, wings, sometimes long after apparent 

 death; corroboration of laboratory results with 

 results from the field as far as possible; dif- 

 ferent results with different brands of CS^; 

 corroboration with previous published state- 

 ments. 



Method and Apparatus Described; Compu- 



' Abstract of paper read before the Association 

 of Economic Entomologists at Philadelphia at 

 their last annual meeting. 



tation. — The necessary crudity of the appara- 

 tus and method described is evident, and must 

 render the results in the case of insects of any 

 size not even approximate. An insect as large 

 as Ectoljia, or Apis melliftca, for example, or 

 the larva of the western peach-tree borer, or 

 that of the Mediterranean flour moth, evi- 

 dently displaces so much of the gaseous con- 

 tents of a vial when introduced, as to render 

 absurd the proportions of gas to atmosphere 

 as given. Even in insects smaller than these 

 there is undoubtedly an error due to displace- 

 ment, yet the writer believes that the method 

 described here comes as near demonstrating 

 facts in this connection as possible, particu- 

 larly in the case of very small insects, and it 

 has certainly brought out interesting results, 

 from which we raay select what appears au- 

 thentic. 



A large number of homeopathic vials were 

 secured, of the same size (homeopathic 2 gram 

 vial No. 1,657 with patent lip), also pieces of 

 flexible rubber piping of such a size as to fit 

 tightly over these vials. Into one vial a drop 

 of CSj was allowed to fall from a medicine 

 dropper, and the mouth of this vial imme- 

 diately placed against the mouth of another 

 empty vial, the rubber tubing referred to 

 serving to hold the two vials closely together, 

 and preventing any egress of gas, or entrance 

 or exit of atmosphere. 



The average capacity of these vials was 

 8.7 c.c, and it was upon this basis that our 

 calculations were made. The volume of gas 

 coming from one drop of CS^ equaled 4.35 

 c.c, and, therefore, filled half a vial. 



It is evident, therefore, that the union of 

 the first two bottles, made immediately, before 

 the gas had an opportunity of driving out any 

 of the atmosphere, caused a mixture of one 

 part of gas to four of atmosphere; the second 

 change, one to eight ; the third, one to sixteen ; 

 the fourth, one to thirty-two, etc., or, inter- 

 preting it with reference to the liquid volume 

 of CS, to the atmosphere, we find that the 

 union of the first two bottles equaled one part 

 of liquid CS^ to 1,494 parts of atmosphere, or 

 in round numbers, 1,500 parts of atmosphere; 

 the second change, one part of liquid CSj to 

 2,988 parts of atmosphere, or in round num- 



