ASSEMBLING. 



347 



and this was always on the windward side of the marsh. 

 The females were enclosed in a moth trap (Plate 54), 

 which was painted on the outside with a mixture of castor 

 oil and resin, and placed a few feet above the ground. The 

 second station was established directly to leeward of the 

 first, and at a measured distance from it. In many cases a 

 third and even a fourth station was established at a known 

 distance from the first and other intervening stations. It 

 was often found necessary to establish three or even more 

 stations, a short distance apart, on the arc of a circle, the 

 radius of which was a known distance from the trap, to 

 compensate for the veering of the wind, which sometimes 

 carried the scent of the female out of a direct line to the 

 stations first established. 



Marlving the Males, — In order to carry on this work and 

 obtain results at all satisfactory, it was necessary to adopt 

 some system of marking the males which were to be liber- 

 ated, in such a way as to enable one not only to recognize 

 them afterwards, but also to determine from what station 

 they came. At first they were marked by cutting a small 

 notch in a certain part of the margin of the wing, with fine 

 scissors. This method, while not apparently injuring them 

 in any way, was objectionable, because of its being a muti- 

 lation which might afiect the results more or less, and 

 therefore it was abandoned in the later experiments, and 

 water-colors were used. It was found impossible to make 

 the colors adhere to the wings, when mixed in water; but 

 fifty per cent, alcohol was found to mix well with dry car- 

 mine colors, and, when applied to the wing, made a tolerably 

 permanent mark. There was no difiTerence in the results 

 obtained from moths marked in the two ways. In marking, 

 the color was applied, by means of a soft brush, to a par- 

 ticular spot on the wings, a difierent mark being used for 

 each station, and a difierent set of marks each day. The 

 male moths were marked and boxed each morning, the 

 marks recorded, and the moths taken into the field. The 

 females were enclosed in the cage of the trap at station Xo. 

 1, and the males were liberated at the other stations accord- 

 ing to their marks. In this way it was possible, when a 

 male was taken at station No. 1, to determine from which 



