DISTRinUTION OF ANIMALS AM) PLANTS IN FELSTEAD, ESSEX. 193 



of the Trout. Allowing this to be a reasonable solution of sudden 

 changes, it throws no light on such questions as the apparently 

 permanent distribution of different species in the different parts of 

 the stream. Thus, below the W'althams, Perch and Pike have been 

 observed for, I believe, all the years of the present century, and 

 many persons can speak to a number of species permanently estab- 

 lished there which have no representation further up stream. 



Pond fish show great tenacity of life or adaptability to circum- 

 stances. This becomes very obvious in the event of a dry summer. 

 Ponds are then sometimes reduced to mud, and all traces of fish 

 disappear ; yet, after the lapse of one or two seasons, wnthout re- 

 stocking, the same kind of fish will be found in the pond as before 

 the drought. I have observed this to occur more than once. This 

 adaptability to circumstances shows itself in another way. In certain 

 ponds in this neighbourhood fish do not attain their average size, but 

 (probably from insufficient food) spend their lives and reproduce 

 their species as dwarfs. In the case of Tench this is notorious. If 

 we allow the weight of that fish to be two pounds when full-grown, 

 we shall have to divide that weight by eight to give the maximum 

 weight of the largest fish in some of the Tench ponds here. It 

 certainly is not common in other organisms to find generation after 

 generation reproduced under such untoward circumstances. Experi- 

 ments with these Tench have shown that they are capable of con- 

 siderable increase in size. A number of fish were transferred to a 

 pond in which much phosphatic matter had accumulated. These 

 fish grew very fast, and attained the normal size quickly. The 

 experiment has been again and again repeated, with similar results. 

 This, I think, goes to prove that the distribution of fish in the river 

 is independent of lack or abundance of food. 



Although there are agencies independent of artificial stocking, 

 by which freshwater fish may be transferred from one pond to 

 another, I do not think that in this locality these extraordinary 

 agencies, as they may be called, are often brought into play. My 

 reason for making this statement will soon appear. The table on 

 next page represents the fish fauna of some ponds included within 

 a circle, with a radius of a mile, having its centre about a mile south 

 of Felstead Church. 



This is the present distribution of fish in those ponds. It was 

 substantially the distribution of thirty-five years ago, as I can person- 

 ally testify, and I have evidence to the same effect, the result of a 



o* 



