i8 
F. STOWARD, D.SC. : 
cocoons, were used resulted in showing that they survive after 
immersion in a solution of formalin (i pt. to 15 gals, water) for 
48 hours, or of mercuric chloride (1 oz. to 8 gals, water) for 30 
hours. 
The use of mercuric chloride or of lead arsenate as a preventive 
against infestation is unsatisfactory. Uninfested tubers after a 
steep of half an hour’s duration in mercuric chloride solution 
(1 oz. to 8 gals, water) or in a suspension of lead arsenate for five 
minutes, subsequent drying and exposure to infestation were 
as readily and extensively attacked as tubers which had not 
been subjected to treatment. Thus in these experiments separate 
lots of uninfested treated tubers, placed in properly closed steri- 
lised receptacles, were exposed to infestation from (a) adult 
larvae, (b) juvenile larvae, the latter derived from eggs deposited 
by moths introduced at the time of the initial establishment of 
the experiments. In either case the tubers were infested, the 
larger proportion of the eyes destroyed, and the infesting objects 
completed their life cycle as rapidly as in the case of similarly 
established experiments in which the tubers were not subjected 
to immersion in either of these preparations. 
Spraying of uninfested tubers for the retardation of in- 
festation 'has not furnished satisfactory results. Several lots of 
uninfested tubers thoroughly sprayed with one or two per cent, 
phenyle, a substance possessing a repellant odour, or with 
freshly prepared copper sulphate-soda mixture of the strengths 
above mentioned, then dried and exposed to moth infestation, 
as readily succumbed to it as did similar but unsprayed 
material. Under the selected conditions employed in this ex- 
perimental enquiry steeping or spraying methods of treatment 
as an effective means of ensuring the destruction of the infesting 
agent or of preventing infestation of tubers have proved to be 
quite ineffective. 
The employment of finely powdered air slaked lime or 
mixtures of lime" and sulphur, or lime and Paris green, in varying 
proportions, applied as a dressing to uninfested tubers, while 
affording a small measure of protection against the pest under 
certain circumstances, have not furnished a reliable means of 
preventing infestation. Their principal drawback is that on 
sprouting protrusion of the sprouts through the thin layer of 
powdered substance takes place and renders the tuber readily 
open to infestation. 
Extensive series of experiments on the use of carbon bi- 
sulphide as a fumigant used solely for the annihilation of the 
pest have shown that ( a ) the destruction of the larvae either in 
the substance of the tuber or external to it is accomplished by 
fumigating larva infested tubers with this compound at the 
rate of 1 or 2 lbs. per 1,000 cubic feet of space for a period of 16 
