258 
Annual Report of the Consulting Chemist. 
Considerable alarm has at times prevailed in various districts 
when the clover or flax has been extensively preyed upon by 
this dangerous parasite. The appearance was of course due to 
the use of seed (generally foreign) containing dodder. There 
is really no excuse for seedsmen permitting dodder to accompany 
clover seed, inasmuch as the small size of the dodder seed (being 
only half the size of clover) permits it to be easily separated 
by the mechanical process of sifting. When, however, the cul- 
tivator has the misfortune to discover dodder on his farm, he 
should use the utmost diligence to secure its destruction. No 
attempt at tearing the dodder to pieces will destroy it ; indeed 
each separate piece that remains connected with the living plant 
will maintain its independent existence. Permitting the dodder 
to die on the field is also utterly worthless for the purpose of 
securing its extirpation, for the seeds remain, and when the 
spring returns they will germinate. The only efficient cure is 
to burn completely the whole vegetation of the diseased spot.^ 
together with the surface of the soil on which seeds may already 
have fallen. 
Flax and clover crops are not the only ones that may be in- 
jured by dodder. The thyme-dodder, of which the clover- 
dodder is, as I have said, but a variety, has been found on plants, 
belonging to the same genus with the potato ; and my atten- 
tion was drawn last autumn, by Mr. Brandreth Gibbs, to a crop 
of Swedish turnips attacked by this plague. The field was near 
Dunstable, on the Brandreth estate. The farmer, Mr. Scroggs, 
informed me that, two years before, the field had produced a 
good crop of trefoil, which was here and there affected by dodder. 
Mr. Scroggs cut down the clover, leaving the diseased plants to 
die on the ground, and then ploughed them into the soil. No. 
indication of the parasite was detected in the wheat crop which 
followed the clover, but the plough having brought the seed 
again to the surface, it germinated after lying a year dormant, 
and attacked the crop of turnips then growing on the field. The 
suckers of the dodder had penetrated principally the fleshy 
stalk and midrib of the leaves, but not a few of the turnips., 
themselves were also attacked on the upper surface. 
IX. — Annual Report of the Consulting Chemist for 1872. 
DdRTNG the period from December, 1871, to December, 1872, 
057 analyses have been referred to me by Members of the Society, 
being 73 less than in the preceding year, and an increase of 71) 
analyses over the number sent out in 1870. 
