a74 THE ZOOLOGIST. 



April 21, 1887. — Wm. Carruthers, F.R.S., President, in the chair. 



Mr. W. Isaac Spencer was elected a Fellow of the Societj'. 



Mr. Patrick Geddes read a paper " On the Nature and Causes of 

 Variation in Plants and Animals." The fact of organic evolution is no 

 longer denied, but its physiological factors have not j'et been adequately 

 analysed. Even those who regard natural selection as at once the most 

 important and the only ascertained factor of the process admit that such an 

 explanation being from the external standpoint — the adaptation of the 

 organism to survive the shocks of the environment — stands'in need of a 

 complementary explanation which shall lay bare the internal mechanism 

 of the process, — i. e. not merely account for the survival, but explain the 

 origin of variations. The relative importance of the external and internal 

 explanation will moreover vary greatly in proportion as variations are 

 found to be "spontaneous," — i.e. in some given direction continuously. 

 Avoiding any mere postulation of an inherent progressive tendency common 

 to both pre- and post-Darwinian writers, the definite analysis of the problem 

 starts with that conception of protoplasm which is the ultimate result of 

 morphological and physiological analysis, — viz. to interpret all phenomena 

 of form and function of cells, tissues, organs and individuals alike in terms 

 of its constructive and destructive ("anabolic and katabolic") changes. 

 While the external or environmental explanation of evolution starts with 

 the empirical study of the effect of human selection upon the variations of 

 animals and plants under domestication, the internal or organismal one as 

 naturally commences with the fundamental rhythm of variation in the 

 lowest organism in nature. It also investigates the nature of the simple 

 reproductive variation upon which the origin of species as well as individuals 

 must depend, before attempting that of individual variation. The inter- 

 pretation of all the phenomena of male and female sex as the outcome of 

 katabolic and anabolic preponderance is shown largely to supersede the 

 current one of sexual selection, and in some cases at least that of 

 natural selection; e.rf. the specially important one of the origin of such 

 polymorphic communities as those of ants and bees. In such cases 

 natural selection acts not as the cause of organic evolution, but as the 

 check or limitation of it, and acquires importance rather as determining the 

 extinction than the origin of species. The process of correlation, especially 

 that between individuation and reproduction is mooted by the author, and 

 its application to the origin and modification of flowers, &c., outlined. 

 A discussion is given of the embryological and pathological factors of internal 

 evolution, with an outlined application of the whole argument to the 

 construction of genealogical tree of plants and animals. 



A report was read " On the Gephyreans of the Mergui Archipelago," by 

 Prof. Erail Selenka, of Erlangen ; this communication, dealing chiefly with 

 a technical description of the species, a few being new. 



