342 Report or THE HORTICULTURAL DEPARTMENT OF THD 
thoroughly mixing returning it to the same box. The quantities 
of manure were reduced from 5 per ct., 10 per ct., 15 per ct., or 
20 per ct. by weight, to 5 per ct., 10 per ct., 15 per ct., or 20 per 
ct. by bulk, respectively. See Table II. This made the actual 
amount considerably smaller than that given to the same box 
for the previous year. So far as influencing the experiment 
is concerned, it need only be said that the relative amounts 
added to the different series remain the same. Moreover, the 
composition of the manure varied in the different seasons. The 
total amount added to any particular box may be easily calcu- 
lated. In experiments of this kind the exact amount of plant- 
food available to each plant or set of plants cannot be accurately 
determined. AJl that is expected is to know the kind, relative 
amounts and composition of the plant-food which is added to the 
various portions of soil under experiment. 
A further change consisted in the use of a loose lettuce, the 
Grand Rapids, in addition to the Rawson Hothouse head lettuce, 
two plants of each variety being grown in each box. 
The seed was planted Oct. 7, in the same manner as before. 
Germination began to appear Oct. 18. The loose lettuce was all 
cut Jan. 15 and 16. The crop could not be held longer without 
having the most advanced plants begin to deteriorate. 
The head lettuce was harvested Jan. 30. It was not then 
mature; but for lack of strict attention to ventilation and water- 
ing during a period of sunshine following dull weather, tipburn 
had made its appearance. The crop was at once harvested for 
fear that rot might follow the tipburn and vitiate the results 
of the work. 
Some of the facts established both by observation of the grow- 
ing plants and by the weights of the different yields are given 
in the following statements: 
As to the effect of commercial fertilizers when used without 
manure, the nitrate of soda gave best results on the clay loam. 
Sulphate of ammonia gave much the best results with loose let- 
tuce on the sandy loam and was unsurpassed with the head 
lettuce. It should be noticed, however, that this was an excep- 
