86 
ROYAL HORTICULTURAL SOCIETY. 
cieiit in exterminating the pest " or disease in the French vine- 
yards if properly applied and strictly carried out ; and if the vines 
have a fair amount of vitality left when operated on, they will 
thrive well afterwards and bear good crops for an indefinite number 
of years. 
VIII. Notes on " Clover-sickness." 
By J. H. Gilbert, Ph.D., E.R.S., F.C.S. 
Having been informed by Mr. Berkeley that it was his inten- 
tion to make some observations on the subject of " Clover-sick- 
ness " at the Meeting of the Scientific Committee to day, and 
having been requested by him to state briefly the results of the 
attempts made at Eothamsted to grow clover more frequently on 
the same land than custom recognizes as practicable, I have, in 
conjunction with Mr. Lawes, drawn up a summary statement of 
the plan and results of the experiments, partly in the form of a 
short abstract of j^reviously published accounts, but bringing the 
record up to the present date. 
Among the causes which have been assigned for clover-sickness 
may be mentioned : — 
Exhaustion of the soil. 
The growth of parasitic plants which strike their roots into the 
clover and exhaust its juices. 
Destruction by insects. 
The injurious influences arising from the matter excreted by 
the roots of a former crop, or from the decay of the roots them- 
selves. 
The growth of the young plant under the shade of a corn- 
crop. 
With regard to the last supposition, which, in a letter in the 
' Gardener's Chronicle' of May 13th, Mr. Berkeley seems dis- 
posed to adopt, it may be stated that during the period of twenty- 
three seasons over which our experiments on the subject have 
now extended, clover has more frequently been sown alone than 
with a corn-crop, and the failures have been as signal under those 
as under the usual conditions. 
The experiments on the growth of clover with many difl'erent 
descriptions of manure were commenced in 1849, and, with the 
occasional interposition of a corn-crop or fallow, have been con- 
tinued up to the present time. The land is divided into three 
main divisions, each of which comprises a series of six plots. 
