372 SECTIONAL TRANSACTIONS— D, E. 



into displacement receptors and pressure receptors. The former are the more 

 primitive. In vertebrates the transition from the former to the latter type 

 can be shown to be a necessary consequence of the transition from a life 

 in water to a life in air. In insects the pressure-receptor type has arisen 

 independently and both types may co-exist in the same insect. 



Much less is known about the secondary properties of the auditory 

 system on which frequency discrimination and localisation depend. Frequency 

 discrimination is highly developed probably only in birds and mammals, 

 though it exists feebly in fish and probably in some insects. Localisation 

 is poor in man but good in mammals with a moveable pinna, and very good 

 in some insects. 



Mr. J. W. S. Pringle. — Senses of movement and position in the insect (2.45). 



It is well known that man and the higher vertebrates possess a highly 

 developed sense of limb position and muscular tone, which enables them 

 to perform co-ordinated movements. Insects, also the highest members of 

 their branch of the animal kingdom, have senses with a similar function, 

 though their very different general morphology makes for differences in 

 the mechanisms. 



The position sense in man is served to some extent by endings in the 

 joint surfaces. In insects groups of hairs are present in the joints, and the 

 excitation of these varies with the degree of flexion. The force of move- 

 ments is measured in man by the tension set up in the contracting muscles. 

 In insects, by contrast, the most important sense organs are embedded 

 in the skeleton, and react to the resulting compressions. 



By recording electrically the impulses in the nerves it is possible to study 

 in detail the working of these senses. 



Dr. D. Ilse. — Studies on the sense physiology and habits of butterflies (3.15). 



Evening. 



Joint Discussion, with Sections C, E, F, K, M, on Planning the land 

 of Britain {8.0). See page ^86. 



SECTION E.-GEOGRAPHY. 



Thursday, September 2. 



Prof. E. G. R. Taylor. — Robert Hooke and his services to cartography, 

 1666-1696 (10. o). 



Hooke's scientific work was in direct response to contemporary needs. 

 Merchant enterprise necessitated maps, maps necessitated survey, survey 

 necessitated instruments of precision. Hence instrument making was 

 Hooke's constant preoccupation. Meanwhile his services were at the 

 disposal of such contemporary geographers and surveyors as Jonas Moore, 

 John Ogilby, William Morgan, Moses Pitt and Robert Plot. He was 

 adviser to John Adams, whose triangulation of England and Wales, begun 

 in 1 68 1, was to have established the map of England on firm foundations 

 as Cassini had established the map of France. But the support of science 



