186 
Report of Experiments on the 
ably well, and was very rog-ular throughout the plots. It was 
therefore left without further treatment during the winter of 
1851-2. 
Those who have paid attention to the spread of disease in 
clover, on land which is said to be " clover-sick," will have 
observed that, however luxuriant the plant may be in the autumn 
and wintei-, it will show signs of failure in March or April, the 
spread .and final limit of the disease being, however, subject to 
great variation. In the month of March, 1851, symptoms of 
lailure became apparent on many of the experimental plots. It 
was quite plain however that the spread of the disease was much 
more extensive and rapid on some of them than on others. And, 
since such a great variety of manures had been employed, it was 
thought very desirable to determine the effect of tlie different 
conditions of growth so provided, in aggravating, or lessening, the 
progress of the failure. Accordingly, on April 15, when the 
disease had extended pretty nearly to its limits, and the surviving 
plants were showing vigorous growth, a plan of the plots, with 
the patches where the plant had died off, carefully laid down by 
measurement, was made, of which the annexed Diagram is a 
copy. 
The black lines show the division of the plots at the time the 
plan was taken. The dotted line, along the centre of the plots 
marked Series 2, shows the division between the portion which 
was manured with ammonia-salts in 1849, and that which was 
not so manured ; and, as already described, the plots of " Series 2," 
of 1851 and afterwards, to which farmyard-manure and lime were 
then applied, comprised a portion of land on each side of the 
line indicated on the plan by this dotted line ; that is to say, a 
portion which had, and a portion which had not, been manured 
with ammonia-salts in 1849. The shaded portions show the 
patches where the clover-plant had died off. 
On the first glance at the Diagram, it is seen that the plots 
which had not been manured with either farmyard-manure, am- 
monia-salts, or rape-cake (Series 1), were by far the freest from 
disease. The next in order in this respect was that half of 
Series 2 indicated below the dotted line ; that is to say, the por- 
tion of the dung and lime plots which had not been manured 
with ammonia-salts in 1849. The other half of the plots of 
Series 2, namely, the portions which had received ammonia-salts in 
1 849 — the plots of Series 3, which had also received ammonia-salts 
in 1849 — and those of Series 4, Avhich had been manured with 
rape-cake in that year, all show a very great failure of the plant. 
It is, however, equally clear, that the Plots 4, 5, and 6 of these 
Scries (with the exception of Plot G, Series 4) were much less 
affected than Plots 1, 2, and 3 of the same Series ; that is to say. 
