SECTIONAL TRANSACTIONS.— J, K. 383 



Prof. W. McDouGALL, F.R.S. — A new statement of the native bases of 

 intelligent and instinctive behaviour. 



These two closely allied questions are still very obscure and controversial. 

 We may distinguish broadly two kinds of units of innate organisation 

 underlying all instinctive capacity — namely, on the one hand, propensities, 

 and, on the other hand, abilities, some predominantly cognitive, others 

 predominantly executive or motor in function. Abilities are merely 

 * machinery ' without driving power ; they become differentiated and 

 multiplied through all learning processes. The position of any creature or 

 species in the scale of intelligence is in the main a function of the number 

 and variety of its innate abilities ; the richer its endowment of native 

 abilities, the more adaptable will be its behaviour. 



The lower animals have few abilities, and each ability is ' geared ' closely 

 to some one propensity ; such an innate and fixed conjunction of an ability 

 and a propensity constitutes in the strictest sense an ' instinct.' 



In the higher animals more numerous native abilities are linked more 

 loosely to the propensities, so that any propensity may activate any ability. 

 In man this is carried to a further point, and the slow maturation of his 

 native abilities obscures their nature and renders the expressions of his 

 native propensities highly unspecific and variable. 



Dr. R. W. PiCKFORD. — Some observations on reading compound passages. 



SECTION K.— BOTANY. 



Thursday, September 1. 



Dr. T. W. WooDHEAD. — Yorkshire plant ecology. 



Yorkshire provides a greater variety of habit conditions than any other 

 county, and consequently has a very varied flora. The vegetation will be 

 considered in relation to the following natural divisions. In the west, the 

 Pennine Uplands, which include Upper Teesdale with Mickle Fell rising to 

 2,596 ft., the calcareous North-Western Dales, and the Millstone Grit and 

 Coal Measures area of the Middle and Southern Pennines. The Permian 

 ridge extending from north to south, and cut through by the rivers from the 

 western dales, and its significance in plant migration. The great Central 

 Plain, overlaid by glacial and post-glacial deposits, and to the north-east 

 the Oolitic Hambleton and Cleveland Hills and the eastern dales. To the 

 south the Vale of Pickering, and beyond the chalk wolds and wold dales ; 

 to the south-east, the gently undulating Plain of Holderness covered by 

 glacial and alluvial deposits ; and a coast-line ranging from precipitous cliffs 

 to sand dunes and mud flats. The distribution will be considered of 

 northern and southern species which reach their limit in Yorkshire, also 

 the effect of the maximum glaciation and that of the last Ice Age on the 

 history of the vegetation. 



Dr. G. E. Du Rietz. — The problem of bipolar plant distribution. 



In New Zealand, Australia, and southernmost South America isolated 

 populations are found of several boreal species, some of which occur also 

 on high tropical mountains. Analogous types of distribution are found 

 also in many genera and higher taxonomic units. Long-distance migration 

 under present geographical conditions cannot explain all these bipolar 



