CORRESPONDING SOCIETIES 451 



Society and published annually as a Phenological Report ; about the migra- 

 tions of insects in Great Britain by the reports asked for by a Committee 

 of the South-Eastern Union of Scientific Societies, set up for the purpose 

 of collecting and analysing such information. Members of the societies, 

 as individuals, already do good work in all these investigations, but more 

 observers are required and the societies could organise them. 



I have been interested in a rather curious bird-count which has become 

 fashionable amongst the Natural History Societies in Canada and the United 

 States of America — a Christmas bird-count. Each Christmas Daj' a society 

 arranges that groups of its members should make a survey of the birds in 

 definite nearby localities, and a list of every kind of bird and its numbers in 

 each glade, or park, or wherever it may be, is published. I have compared 

 some of these lists year after year, and I feel sure that any such observations, 

 carried out at the same season and in the same localities and repeated for a 

 series of years, are bound to yield results of interest and sometimes of 

 surprising and unsuspected changes. And besides there is the interest 

 imparted to and shared in by the observers themselves. 



Joint enterprises, carefully planned, are profitable enterprises scienti- 

 fically, and while I should have liked to submit to you a list of problems 

 which could best be tackled in this way (and many such problems will occur 

 to anyone familiar with the trend of natural history investigation) I must 

 pass to another line of attack upon biological problems open to you. 



Biological Problems for the Individual. 



It may be that in some of the societies the number of members interested 

 in natural history is too small to permit of joint enterprises, or it may be 

 that some members prefer the independence of the lone hand. I commend 

 to them the biological type of problem. A most striking difference between 

 the collector's method, which predominated for so long, and the biological 

 method, lies in the material of their study. The collector, and on the whole, 

 the list maker, are looking for rarities, their material becomes more scarce 

 the longer they labour, their collecting of rarities reduces still further a stock 

 which may be dwindling, even towards extinction. Such things are un- 

 desirable. On the other hand, the student of life requires no rare material, 

 the more common a creature is the better it suits his method, for his object 

 is to learn something of the principles which regulate the lives of animals, 

 and the more abundant his material the greater likelihood is there of the 

 success of his observations. And there is still opportunity even in the most 

 familiar creatures for the gain of new knowledge, if the inquiry be pushed 

 far enough. Often it need not be pushed very far. 



Take the common house-sparrow — I can think of nothing more familiar 

 or more easily observed. My experience of house-sparrows is that every 

 full clutch of eggs contains one egg slightly different in shape and coloratibn 

 from the rest. Is that the first egg to be laid or the last, and does it produce 

 a sparrow different from the others in size or colour or sex ? I doubt if 

 anyone knows. Certainly no one knows exactly how long sparrows' eggs 

 take to incubate in different districts, or how long the fledging period lasts 

 under different conditions. Are the young birds fledged and able to fly 

 sooner when food is plentiful or when the air temperature is high, than when 

 food is scarce and the weather is cold ? The answer would have a bearing 

 on a fundamental biological problem — the relationship of growth and 

 development to nourishment and warmth. Another point which seems to 

 me to have some interest : do the second and third clutches of a pair of 

 sparrows take exactly the same time to hatch and fledge as the first clutch ? 



