228 DR. R, ANGUS SMITH ON THE PRODUCTION 



or animalcular life in immense variety, and we shall also find 

 that if we allow it to stand vegetable life will show itself 

 in great abundance. The hilly districts of our own island 

 do not contain water of this kind. I was extremely sur- 

 prised, on taking my microscope to the north-west of Scot- 

 land, to find that the ditches were so meagre of living crea- 

 tures. A green pool was scarce, and when found it was 

 small, whilst on examination it was vivified by very few 

 living forms. The whole hills in fact were either void of 

 matter capable of putrefaction, or they were so rapidly 

 washed that the putrefying matter was passed at once into 

 the soil. The moisture, too, produces no corruption ; it is 

 water in rapid motion filled with air, and rapidly traversing 

 the soil, oxidising all the small portions of putrid matter 

 that may be forming in the soil, and fixing the products 

 in the earth. The animal life is repressed, i.e. the life of 

 such living things as arise from decomposed plants or 

 animals. But why should this be ? Let us push the 

 argument further. If grass grows in such places there 

 must be food for plants, and elements for the production 

 of infusoria. It is true that grass grows, but not in great 

 vigour, and as the rain passes very rapidly through the 

 soil there must be very little matter kept soluble at one 

 time. The plants must be fed by small although by very 

 frequent, meals. Besides, the soil is not deep ; the power 

 of retaining soluble matter is therefore small ; the stock 

 of food laid up over the whole district, in other words the 

 material from which such animal life must spring, is ex- 

 tremely scanty. Now I am not prepared to say that 

 all unhealthy districts actually contain a large amount of 

 matter either putrefying or forming into animalcular life, 

 but it certainly is the characteristic of what seems to me 

 to be the soil most blamed ; there may be some, as already 

 stated, where other causes arise. This state of soil is that 

 of all our lower lands ; the ditch water swarms with life ; 



