general Zoological changes. 67 



exertions which local authorities, as municipalities, or even in- 

 dividuals have made, within their own immediate jurisdiction, 

 towards effecting the same purpose. These measures have 

 been injurious or beneficial, in proportion as the theory on 

 which they were based was erroneous or just. Thus, about 

 thirty years ago, many parishes in Thuringia paid a certain 

 premium for each sparrow's head brought to the mayor, with 

 a view of protecting their white crops from the depredations 

 of that bird. But this measure was found to be incompatible 

 with the preservation of their orchards and green crops from 

 insects. On the other hand, the very serious damage which 

 the hamster, {Mus Cricetus), did in the fields of Gotha, and 

 the neighbouring villages, where the deep loamy soil encou- 

 rages the multiplication of that animal, to an intolerable de- 

 gree, was most properly and effectually repressed by a general 

 extermination of that species, made at the expense of the mu- 

 nicipality and parishes. An individual of Dantzic has left a 

 legacy, out of w r hich 100 dollars are annually paid to the fish- 

 erman of that town, who makes use of the widest mesh in the 

 exercise of his calling ; but some one of the profession may 

 think it to his interest to use such a wide mesh as to catch 

 nothing in his net, except the premium, and others may find 

 it more profitable not to try for it at all. 



We have still to consider one subject connected with the 

 progress of civilization, which has acted a most prominent 

 part in modifying the relative proportions of the lower ani- 

 mals all over the globe, and has been superadded to every 

 form of government, the pure hierarchical perhaps excepted, 

 viz. commerce. This extends its influence far beyond the li- 

 mits of the territory subjected to the direct agency of the 

 respective nations. The whale-fishery, for instance, in con- 

 sequence of which a few species of the large Cetacea, former- 

 ly very numerous throughout about two thirds of the surface 

 of the globe, have already become very scarce, and are almost 

 entirely driven from many seas ; and if we try to appreciate 

 how it must have affected the relative numbers of the different 

 inhabitants of the ocean, through all the links of the chain 

 which they form, in their dependence on each other, we shall 

 form an adequate idea of what commerce has effected, in this 

 respect alone ; and were it possible to reduce the total effect 

 of the whale-fishery to a strict calculation, we should without 

 doubt arrive at the most surprising results, whereas, for the 

 present, we must content ourselves with referring to that 

 source a few insulated phenomena, such as the well-known 

 multiplication of the dog-fish, and other fish of prey, in the 

 German sea. The cod and herring fisheries must likewise 



