EXPERIMENT STATION BULLETINS. 469 



insect fiimigants are more or less narcotic in their action. Shiro Tashiro 

 lias found, by means of liis new apparatus for estimating exoeedinjjly 

 minute quantities of carbon dioxide produced in nen^e fibres, that ether 

 and urathane "diminish COj production from isolated nerve fibre"* — 

 although he was not working with insects. 



CONCERNING THE INFLUENCE OF GASOLINE-VAPOR, ETC., AND LIME- 



SULPHUR SOLUTION UPON THE PASSAGE OF OXYGEN, RESPECTIVELY, 



THROUGH FAT OR LIPOID, AND CERTAIN WAX MEMBRANES. 



It has been made clear that gasoline deleteriously affected the re- 

 ductase activity far more quickly and severely than it did that of the 

 oxidases; and further that, since the presence of a strong reductase 

 tended to partly hold in check oxidase-activity, the quick lowering 

 of reductase-activity in a gasoline-treated extract caused the latter to 

 show greater oxidase power for a while than an untreated check of the 

 same extract. This was true when the test was made with fresh extract 

 in the presence of gasoline vapor. But in such tests as the last, made 

 with extract that had already lost the greater part of its reductase- 

 activity, the fact will be remembered that a less amount of oxygen was 

 used by the "extract plus hydroquinone solution" (and less quinone was 

 formed) in the presence of air containing gasoline vapor than by the 

 check in pure air. 



When an extract a few hours old was treated very strongly with gas- 

 oline and then test was afterward carried on in fresh air, however, 

 oxidase activity did not appear to have been greatly lessened. The 

 suspicion therefore presented itself that the lessened oxidation of hydro- 

 quinone occasioned by the extract in the presence of gasoline-vapor, as 

 well as also the lessened use of oxygen by insects deeply under the in- 

 fluence of gasoline-vapor, was partly due to some other cause than injury 

 of the oxidase or reductase by gasoline. 



As has been mentioned several times, the first and most uoticpable 

 fact in connection with the tissues of an insect strongly treated with 

 gasoline vapor, as well as with tissue-extract so treated, was the solvent 

 action of the gasoline upon the fats and fat-like bodies (lipoids) ; or, 

 looked at from the other point of view — the insistent fact was the solu- 

 bility of the tissue-fats and. lipoids for gasoline vapor. Lipoids were 

 found to be present in or around the cells of insect tissues. For example, 

 a serai-transparent lipoid residue was obtained by extracting the washed 

 muscles of P. cornutus with ether containing a little alcohol. This was 

 perhaps to be expected, since the almost universal occurrence of lipoids, 

 especially such as lecithin, in animal cells and animal fluids has been 

 recognized for several years. This lipoid residue obtained from the 

 washed muscles of P. cornutus absorbed gasoline readily. The condition 

 therefore seemed to obtain that wherever the lipoids might be found, in 

 the body fluids (blood) — where they certainly were present — in the 

 protoplasm boundary layer of the cells (Overton) or in the complex of 

 the cell-protoplasm ilself, gasoline would surely also be present in an 

 insect under the influence of that insecticide. Tn any such case the 

 insect tissue cells would be enveloped by blood holding gasoline in solu- 

 tion ; the ends of the trachaeoles would be permeated by gasoline. Could 



•Am, Jour, of Physiol., Vol. 82. 101.3, No. 11, p. IIT. 

 See also same Jouruiil pp. 137-145. 

 See also same Journal Vol. 34. 1914, pp. 405-413. 



