A GARDEN IN VENICE 



this, sulphur ferruginous, is carried, as I have 

 said, underground to the vasca. The family 

 mosquito, thinking the vasca a safe place in 

 which to lay her eggs, is betrayed, for the sulpho- 

 iron kills them, as it killed my goldfish and 

 lilies. 



Lastly, we have not the earthworm, and I at 

 first thought Venice threw a doubt on Darwin's 

 earthworm theory that makes them the makers 

 of all vegetable mould. Was it the exception, 

 perhaps, which proved the rule ? Or are there 

 not rather in the difficulties of our cultivation 

 some slight proofs to be found of the great man's 

 insight. 



Darwin tells how the earthworm prepares the 

 ground in an excellent manner for the growth of 

 all fibrous rooted plants, and seedlings of all 

 kinds ; that their working in it is as that of the 

 gardener who prepares fine soil for his choicest 

 plants, and that, mixing it with their humus, 

 they leave it in a state well fitted to retain mois- 

 ture. They burrow, too, to a depth of five or 

 six feet, and their burrowings allow the air to 



r 2 131 



