132 Notes on Chemotrqpism in the House-Fly 



them to be formed during fermentation, with increased positive chemo- 

 tropic effects. 



After October 5th the flies unfortunately became lethargic, and the 

 following figures suffer very much from the insects being in this con- 

 dition. 



It is therefore not possible to determine the exact position of valerianic 

 aldehyde in relation to the above reagents. Exp. 9 shows it to be 

 strongly attractive under the prevailing conditions, but does not give 

 an idea as to its holding a place between amyl acetate and valerianic 

 acid, which, on the face of what has gone before, is quite probable. 



To come to some conclusion as to what arrangement of molecular 

 grouping furnishes these substances with their positive chemotropic 

 powers, records were taken of the numbers of flies caught respectively 

 by four alcohols, three aldehydes, and three acids — as here named with 

 their chemical formulae: 



Methyl alcohol, H.CH 2 OH; ethyl alcohol, CH 3 CH 2 OH; amyl alcohol, 

 CH 3 (CH 2 ) 3 CH 2 OH; benzyl alcohol, C 6 H 5 .CH 2 OH. 



Valerianic aldehyde, CH 3 (CH 2 ) 3 CHO; benzaldehyde, C 6 H 5 CHO; 

 cinnamaldehyde, C 6 H 5 (CH) 2 CHO. 



Valerianic acid CH 3 (— CH 2 ) 3 COOH; benzoic acid + ethyl alcohol, 

 C 6 H 5 .COOH + CH 3 CH 2 OH; cinnamic acid + ethyl alcohol, C 6 H 5 (CH) 2 

 COOH + CH 3 CH 2 OH. 



All these were used undiluted, except for the two solids benzoic acid 

 and cinnamic acid, of which saturated solutions were prepared in pure 

 ethyl alcohol. 



Experiment 8. Alcohols. 



Date:— October 6th-7th. 



General weather conditions: — Warm, dull. 



Duration of experiment : — 23 hours. 



Flies caught 



Substance Amount , ■ N 



c.c. <J $ Total . 



Methy alcohol 20 



Ethyl alcohol 20 1 2 3 



Amyl alcohol 20 1 1 



Benzyl alcohol 20 1 1 



Percentages are not given, as the number of the flies caught is in- 

 sufficient. The only fly caught by benzyl alcohol probably entered the 

 trap by accident. 



Ethyl and amyl alcohols are the only two attractive ones. 



