468 TRANSACTIONS OF SECTION D. 



As regards the subjects of study, work has been distributed as follows : 

 Mammals (1,569 papers) ; Arthropods (863) ; Fishes (730) ; Organography (594) ; 

 Birds (527) ; Molluscs (388) ; Worms (357) ; Reptiles (334) ; Amphibia (233) ; 

 Coelenterates (200) ; and Echinoderms (62). Of works of a general or more 

 encyclopaedic nature there are 471. The seventeenth-century revival related 

 chiefly to Mammals, but concerned to a lesser extent Birds, Fishes, and 

 Arthropods, and to a slight extent Reptiles and Molluscs. In the nineteenth- 

 century revival, Mammals, Arthropods, Fishes, and Organography, in the order 

 mentioned, play the leading part, followed by Birds, Molluscs, and Reptiles. 

 Even in the first half of the eighteenth century, the slackest period since the 

 seventeenth-century revival, interest in the anatomy of Mammals is well main- 

 tained. 



Each of the Figs. 1-4 shows a certain periodicity of output, especially 

 during the nineteenth century. Roughly speaking, the periods are equal ones 

 of about ten years each. In other words, for each decade there is a rise and 

 fall. This periodicity is well marked in the graph for Germany. 



It is not always possible to compare visually the relative bulk of publica- 

 tions at stated intervals, owing to the fact that a large number of works for 

 one year give undue prominence to that period. In order to make comparisons 

 of this kind more readily, graphs have been prepared which show the rise and 

 fall by obtaining the aggregate of the publications for successive periods of five 

 years each and plotting the average. 



If Fig. 1 be compared with the graph illustrating the history of Zoological 

 Museums already published, it will be noted that in the latter the seventeenth- 

 century revival is not represented, but that between 1747 and 1770 the influ- 

 ence of Linnaeus and Buffon produced an effect which would naturally be want- 

 ing in an anatomical graph. The nineteenth-century revival, however, is 

 also to be found in the museum graph. The period lies between 1809 and 1847, 

 and curiously enough the maximum occurs in exactly the same year as in the 

 anatomical graph, viz., 1835. 



9. The Insect Associaiioit of a Local Eiivironmental Complex. 

 By Alfred E. Cameron, M.A., D.Sc, M.Sc. 



An association is a group of animals uniform over a considerable area, and 

 its unity is dependent upon the migration of the individuals from one stratum 

 to another at different times of day, or at different periods of their life-histories. 



The environment is a complex of many factors, each dependent upon 

 another or upon several others. A change in any one effects changes in one 

 or more others. The most important environmental factors are water, atmo- 

 spheric moisture, light, temperature, pressure, oxygen, carbon dioxide, food, 

 enemies, materials used in abodes. In nature the combinations of these requisite 

 for the abode of a considerable number of animals are called ' environmental 

 complexes.' Local complexes are often referred to as secondary or minor con- 

 ditions or as edaphic or soil conditions. 



It is very probable that the plant and animal associations will prove to be 

 co-extensive. 



In the study of an insect association one has a choice of two methods : 

 (1) One may treat of a species, genus, family, or order as one's unit and show 

 the relation of each one severally to the environment. (2) The other method, 

 which is more comprehensive, treats the whole of the environmental factors as 

 a .single entity to which all of the insects of the various orders respond in 

 unison. The latter was the method adopted by the author. 



The physiogTaphy and topography of the district. Holmes Chapel, Cheshire, 

 were reviewed in a general way and the geological facts summarised. Such a 

 proceeding is necessary because the plant association, so important in relation 

 to insect life, is largely determined by the nature of the soil of the district as 

 well as the exposure and other factors. The vegetation of the Holmes Chapel 

 area is mesophytic, and the plant association is of the grassland mixed wood 

 type. 



Records of barometric pressure, air temperature, and soil temperature were 

 kept for the period during which the work lasted. In many cases it is difficult 



