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time this gas has been largely used by myself and others. I have yet 
to hear of the first instance wherein a single human being has received 
any serious injury either from, the gas itself or from the chemicals 
employed to produce it. Occasionally a barnyard fowl that may chance 
to be in the tree at the time it is treated will be sent into the next 
world by the shortest practical route: and small birds, as well as liz- 
ards, sometimes share a similar fate, but cases of this kind are rare, 
and could in most instances be prevented by exercising due precaution. 
At the present price of the chemicals used, the cost of treating citrus 
trees with this gas will vary all the way froni 5 cents to $1 per tree. 
This latter sum may seem to be an exorbitant one to pay for ridding 
an orange tree nf rhe scale insects that infest it. and yet our fruit- 
growers ,rmd themselves well repaid for expending so large a sum of 
money for this purpose. One of the greatest pests at present infesting 
the orange groves of southern California is what is commonly known 
as the Black Scale Lecanium 'Aea Bernard : while this pest does not 
devitalize the tree it infests to the same extent that some other kind> 
do. still the black fungus, which always accompanies its attacks, ren- 
ders the fruit so unsightly that it is necessary to wash the latter before 
placing it upon the market. The cost of thus washing a box of oranges 
amounts to about 20 cents per box. An orange tree large enough to 
require the expenditure of |1 to treat it with the gas will yield on an 
average fifteen boxes of oranges, and to wash these would require the 
expenditure of about 63. as compared to $1 to fumigate them. This 
fact is not merely a theoretical one. but has been demonstrated again 
and again by different orange-growers in this district. Not only is it 
cheaper thus to fumigate the fruit on the tree, but it also leaves the 
fruit in better condition, since, as is well known, washing oranges 
impairs their keeping qualities. In addition to this, the fumigated 
tree, being rid of the pests whose attacks continually weaken its 
vitality, will be in much better condition to produce a superior grade 
of fruit. 
At a recent meeting of the county horticultural commissioners of 
southern California, one of the commissioners. ^Ir. B. J. Perry, re- 
ported having treated 47,000 citrus trees, at an average expense of 
less than 25 cents per tree. This is but slightly in excess of what it 
would cost to spray them, and this slight difference in the cost is more 
than counterbalanced by the betrer results obtained, the less labor 
involved, and the better condition the trees are left in after tne opera- 
tion is completed. 
The following paper was then read 
