( xxxvi ) 



vatiou. In certain Pierines, as for instance Catopsilia jiorella, 

 in addition to a Co^ms-like patch on the hind wing, there 

 existed a tuft or fringe of hair-like scales near the inner edge 

 of the fore wing. The close proximity of the latter to the 

 former structure suggested that it might be used in some 

 such way as the terminal tuft of the butterfly exhibited by 

 Professor Poulton. The speaker had observed, as mentioned 

 in his Presidential Address in 1910, that the scent- patches in 

 Pierines were furnished with a special distribution of tracheae. 

 The ultimate branches of these were difficult to trace, but in 

 some instances they appeared to have an unmistakable con- 

 nection with the sockets by which the scent-scales were 

 articulated with the membrane of the wing. He thought at 

 the time that he was the first to observe this peculiar con- 

 nection of tracheae with the scent-patch, but had since found 

 that he had been anticipated by Fritz Miiller, who saw every- 

 thing. Lt.-Col. Manders had also noticed it, though his 

 observations on the point were at present unpublished. Dr. 

 Dixey went on to say that he had put forward the suggestion 

 that by the means of this tracheal supply, the products of the 

 special secreting cells which had been observed (though not in 

 actual connection with the scales of a scent-patch) by Weis- 

 mann, Glinther and others, might be propelled, as it were by 

 a vis a tergo, into the scent-scale, and so, in a volatilised 

 condition, into the outer air. In many cases of isolated 

 scent-scales furnished with a proximal disc, an evident aper- 

 ture existed in that part of the disc which was included in 

 the socket. Through this the interior of the scale might be 

 put into communication with the secretory apparatus lodged 

 in the membrane of the wing. In these cases the escape of 

 the odour into the open air doubtless took place through the 

 distal fimbriae with which scales of this type were usually 

 provided ; but Dr. Lamborn's observation suggested that the 

 anal tufts acted as mechanical dispersers of an odour produced 

 elsewhere, rather than as themselves directly connected with 

 a secretory apparatus. The fact that an Catopsilia not only the 

 Colias-like patch, but also the tuft or fringe, possessed a special 

 supply of tracheal branches, seemed adverse to the idea that the 

 fringe, in tliis instance, acted as a mere scent-sprinkler; that 



