116 REPORT OF THE COMMISSIONER OF AGRICULTURE, 
formed by a layer of rubble, covered with hydraulic cement; the walls and floor 
are covered with asphalt. The ceiling, made of iron and brick, is covered witha 
layer of sand, over which is a floor, which in turn is covered with a large quantity 
of sawdust. To this ceiling are suspended three long boxes of galvanized iron, in 
which there circulates a concentrated solution of chloride of magnesium, which 
only freezes at — 20° C. This liquid is cooled by suitable refrigerating machines, 
and is carried from them in pipes to the boxes of the hibernating room. The air 
contained in this room is dried by masses of quicklime placed in wooden boxes; 
this air is renewed through openings in the doors and windows, and they are also 
careful to open for an instant a little before sunrise the windows which give on the 
surrounding rooms. 
The refrigerating machine is one employing sulphurous acid after Pictet’s method. 
The receptacle in which the liquid sulphurous acid is gassified is entirely plunged 
into brine, which is consequently cooled as the apparatus operates. This cold brine 
is forced by means of a pump into the troughs on the ceiling. At the same time 
another pump takes the sulphurous gas and liquefies it in a second receptacle, from 
which it is made to run from time to time into the first. 
To assure the regularity of temperature in the cold rcom two Pictet machines 
are used alternately and prevent the suspension of work in case of accident to one. 
This arrangement enables Signor Susani to safely hibernate large quantities of 
eggs, which amount sometimes to more than 60,000 ounces per year, though the 
capacity of the chamber reaches 100,000 ounces. 
On each side of the hibernating room are the rooms occupied by 
the microscopists and their helpers. The division of labor in the 
preparation and examination of moths has here been carried to great 
perfection, the cells containing the eggs passing through the hands 
of three operatives before they reach the microscopist. The moths 
are carried to her already crushed in a small mortar, which occupies 
one compartment of a box, in the other division of which is placed 
the corresponding cell of eggs. Twenty of these boxes: fill a tray, 
which serves to carry the stock through the different parts of the 
room while the moths are submitted to the various examinations. 
The microscopist then examines the twenty moths, one by one, 
placing tin tags bearing her number on the boxes of those which 
have shown corpuscles. The tray is then passed to the table of the 
‘first comptroller.” 
At this table an attendant takes small portions of the liquids of 
each of the healthy moths and mixes them intimately in a small por- 
celain jar, the contents of which is examined by the comptroller. Ti 
he finds no traces of the pébrine after examining several slides from 
this lot, the jar containing the mixture is sent on to the second comp- 
troller, who has portions of it mixed with like portions of the con- 
tents of several other jars, and submits the new mixture to another 
examination. If, on the other hand, the first comptroller has found 
disease in the mixture examined by him, the tray from which it was 
taken is sent back to the microscopist for further examination. 
The cells passed by the second comptroller are then sent to a man 
who separates the pure eggs from the impure. In addition to the 
force of microscopists and their immediate helpers a large force of 
laborers, all girls and women, are occupied in the cleansing of the 
mortars and other apparatus used. The cells of unhealthy eggs are 
at once destroyed by ie while those containing good ones are turned 
inside out and hung in the loft upon racks, under which sheets are 
laid to catch any eggs that may drop. The eggs are washed from 
the cloths later in the year when the microscopical work is termi- 
nated, A 
The advantages claimed for this system of ‘‘double control” are 
denied by many persons whose opinion on the matter is well worth 
consideration. Their objections to it are based on the following 
