METHODS IJ>7 



to go on an expedition to some remote part of the world. I have often 

 looked at the gratings round the roots of trees in London streets, and 

 wondered what kinds of animals live there, how they differ from other 

 tree-root communities elsewhere and from each other in the same 

 street, how colonization began, what changes of fortune affect them, 

 and why. Choose a subject that is near at hand, for you will not live 

 long enough to make a thorough study of your animal if you have to 

 travel far merely to see it. 



For those with no scientific training, there is still a great amount of 

 simple observation that could be of scientific importance, for animals 

 are watched in their natural environment by very few people who are 

 also willing to write about what they see. But the observer should 

 also be willing to acquaint himself with the hterature on the same 

 subject, and should read the observations on literature in a later 

 section. Tinbergen (1953) has suggested that one animal is enough 

 for one person. I have much sympathy with this point of view, but 

 perhaps an occasional excursion into some other field is advisable to 

 broaden the outlook. 



I believe that the animals being studied should receive as little inter- 

 ference as possible, for as soon as one does anything to them, they are 

 no longer "at home." By all means use any laboratory methods to 

 study the environment, but leave the animals themselves alone. In my 

 tadpole work, I decided in advance that my sample need not exceed 

 ten tadpoles from each pond each week. This small number was no 

 more than one additional dragon-fly larva could destroy, so that I 

 could hardly be upsetting the facts I was studying by more than a 

 trifling addition to the hazards already present in the pond. I would 

 have preferred not to collect at all, but I could not get my information 

 in any other way. Knowing what I wanted, there was a temptation 

 when walking up to a pond to start collecting at once. I resisted tliis, 

 and dehberately spent the first period at the pond merely looking into 

 it, so that I came to know what the animals did before my net touched 

 the water. Elton has some useful advice and should be consulted. 



Pond-J&nding 



Some areas contain so many ponds that it is easy to find them. But 

 the ponds thus foimd may not be the right sort of pond. Other areas 

 have few ponds. Ponds may lie unsuspected in a hollow in a field that 

 is famihar in another comer, and much time can be lost in searching. 



