ITS ORIGIN AND PEOGEESS. 



9 



tubes, placed closely together, the ends being confined 

 in a sort of rack, made of -wood. Each grille is 

 placed in a small earthenware trough, glazed on the 

 inside, this heing the hest preventive to the growth 

 of confervse. The troughs are placed crosswise in 

 the cistern, and are about six inches wide and four or 

 five deep. A tap at the head of ea;ch cistern permits 

 the water to flow slowly over the range of troughs 

 throughout the cistern. It will be seen that these 

 troughs can, therefore, easily be removed separately 



FKENCH TROUGH AND GRILLE. 



for examination. In the building on the left opera- 

 tions requiring care are carried on. This builduig 

 also contains brick basins for rearing. All these 

 processes are carried on within the buildings, and 

 thus extreme frost, or glare and heat of the sun is 

 avoided. 



The ova formerly was collected, by men who made 

 a business of it, principally from the Ehine, the 



