SECTIONAL TRANSACTIONS.—D 399 
Drosophila super-females; each explanation implies that pallipes has not only 
adopted thelyotokous parthenogenetic ceproduction, but that its chromosome 
complex has become a fixed diploid, one which, moreover, is almost incapable 
of reduction to the haploid condition and, still more unlikely, to a heterogametic 
condition; consequently, in rare and probably unnatural pairing the female 
dispenses with fertilisation, or its ‘ femaleness ’ suffices to destroy the ‘ maleness ’ 
introduced by the spermatozoa, whether the spermatozoa are haploid—c.f. drone 
bee—or of two potentialities—c.f. other insects. 
10. Dr. F. A. Drxey, F.R.S.—On Scent-distributing Structures in the 
Lepidoptera. 
In the Pierine, or ‘ white butterflies,’ the scent-distributing scale is usually 
a rather highly specialised structure, which in many members of the group takes 
the form of a flattened lamina provided distally with a fringe of chitinous 
filaments, and proximally with a fine flexible footstalk. This latter expands 
into an accessory disc, which varies from species to species in size and character. 
The disc is inserted into a specialised socket, within or beneath which are found 
the cells which secrete the scented material. 
Though no doubt exists as to the respective functions of cell and scale, diverse 
views have been held as to the exact mode in which the scent escapes. Weismann 
thought that the secretion passed from the mother-cell by way of disc and foot- 
stalk into channels within the substance of the lamina; that these channels 
were prolonged into the fimbriz, or distal filaments, and so, through terminal 
orifices of the latter, into the open air. Illig, on the other hand, contends that 
there is no proof that the fimbriz are pervious, and attributes the escape of the 
odour to pores on the surface of the lamina. The minuteness of the structures 
involved makes investigation difficult, and the interpretation of the microscopic 
appearances is attended with much uncertainty. The present writer, however, 
finds that the disc is in connection with the subjacent cell, and that a space may 
exist within the lamina. He has failed to find satisfactory evidence of the 
existence of pores. 
11. Prof. A. E. Cameron.—Some Tabanide of Saskatchewan, their 
Parasites and hitherto undescribed pre-imaginal and imaginal 
Stages. 
The material on which the substance of the paper is based was collected in 
northern Saskatchewan with the idea of obtaining information on the early stages 
of the Tabanid family. Only a comparatively few species are discussed—namely, 
Chrysops marens, C. mitis, O. fulvaster; Hamatopota americana; Tabanus 
septentrionalis, 7’. reinwardtii, and 7’. insuetus—and in each case descriptions 
of the pre-imaginal stages which have not previously been published are fur- 
nished. It is felt that whilst the paper is not exhaustive, any additions to 
our knowledge of this important family will be acceptable as a contribution to 
the present rather meagre information concerning the life-histories of our North 
American species. The author hopes to enlarge the scope of the work in future 
papers, a hope which is strengthened by the abundance of the Tabanide in 
Western Canada. In many species the males are unknown, and the author has 
been enabled by careful rearing of the young stages to obtain excellent series of 
the males of the species above enumerated, from which descriptions have been 
made. Parasitism of the 'Tabanide and their general habits are briefly dis- 
cussed, as well as the importance of the eye-markings in the identification of 
species. 
Friday, August 8. 
12. Joint Discussion with Section M on Soil Population. 
Afternoon Excursion to the Forks of Credit River. 
Monday, August 11. 
13. Presidential Address by Prof. J. W. Gamsur, F.R.S., on Con- 
struction and Control in Animal Life. (Page 109.) 
