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SECTIONAL TRANSACTIONS.—D. 393 
according to several authors, are capable of producing sex-mosaics in 
insects. The study of the large number and great variety of the 
Cephalotes mosaics has not as yet proceeded far enough to enable us to 
estimate their bearing on the hypotheses of Boveri, Morgan, Goldschmidt 
and Whiting. 
Dr. D. M. Wrincu.—The structure of chromosomes (12.30). 
A molecular structure for the chromosome is proposed as a working 
hypothesis. This structure is designed to interpret the findings of the 
cytologists as to the capacity of the chromosome to swell, to contract, to 
grow and to divide ; and to explain in molecular terms the postulates of 
genetics and the nature of the gene. 
AFTERNOON. 
Lt.-Col. R. B. Seymour SEWELL, F.R.S., C.I-E.—Semi-popular lecture on 
The fohn Murray Expedition to the Arabian Sea (2.0). 
(1) The origin of the expedition. 
(2) An account of the ship, H.E.M.S. Mabahiss. 
(3) The scientific staff. 
(4) The itinerary. 
(5) The character of the coasts in (a) The Red Sea. 
(6) The S.E. coast of Arabia. 
(c) Muscat and the Gulf of Oman. 
(d) Zanzibar. 
(e) The Seychelles. 
(f) The Maldives. 
(6) The bottom topography and the different characters of the North- 
east and South-west basins. 
(7) The main trend of the deep circulation. 
(8) The distribution of the fauna, with special reference to certain areas 
in which there seems to be but little or no animal life. 
Exhibition of Prof. J. S. Huxey’s film ‘ The private life of the gannets’ 
(by kind permission of London Films Production Ltd.) (3.0). 
Excursion to the Marine Biological Station at Lowestoft, by kind 
invitation of Dr. E. S. RusseLt, Ministry of Agriculture and Fisheries 
(3-30). 
Exhibition of the following films, by courtesy of British Gaumont 
Instructional Films (9.0) : 
Ameeba ; earthworm; worms; the life of the frog; the life history of 
the blow-fly ; the early development of the sea-urchin ; the life history of 
the tortoise-shell butterfly. 
Tuesday, September 10. 
Symposium on Animal migration (10.0) :— 
Prof. J. Rrrcu1e.—The migrations of terrestrial and aerial mammals. 
Wanderings of limited extent, restricted to short periods, are a common 
expression of the rhythm of mammalian life, and some specialised mam- 
