105 
double. At the top of a peduncle of the usual size and appearance 
are fixed two equal, parallel, and perfect male cones. Mr. Yates 
showed that some approach to this double formation is occasionally 
found in the genus Encephalartos, inasmuch as the axis of the cone 
is sometimes bifid near the summit. 
It was also remarked, that the peduncle of Macrozamia bears leafy 
appendages, and that these have not been found in any other recent 
genus, but are very conspicuous on the peduncles of the fossil Zamites 
gigas, which is found in the oolitic strata near Whitby. 
Parasitism of Rhinanthus Crista-galli. 
Read some ‘ Observations on the parasitic habits of Rhinanthus 
Crista-galli, and its injurious effects on the growth of Barley.” By 
Joshua Clarke, Esq., F.L.S., &c. These observations were made dur- 
ing the last summer in the parish of Debden, in the county of Essex. 
The field contained four acres of barley, the soil a stiffish clay ; the 
Rhinanthus was growing in patches at different parts of the field, some 
of which were much larger than others, and occupying at least half 
the surface, by which about two acres of the barley were completely 
destroyed, and the remaining part of the crop very much injured, both 
in quantity aud quality. The farm consisted of 170 acres, principally 
clay soil, such as is usually called heavy land ; thirty acres of it were 
of barley, about ten of which were destroyed by this plant. This loss, 
combined with other causes, induced the occupier to give it up. 
In regard to the mode by which the Rhinanthus effects the injury, 
Mr. Clarke states that the fibres of the roots attach themselves to the 
fibres of the barley, on which they form small round tubers, or what 
perhaps may be more properly called spongioles, which embrace the 
fibres so effectually, that they suck the juices of the plant so as 
to starve it, and in most instances ultimately destroy it; these 
spongioles are formed of cellular tissue. A correct knowledge of the 
habits and natural history of a plant may lead to its eradication, but 
in this instance it is a matter of considerable difficulty, the ordinary 
method of destroying weeds by a summer fallow being of no avail, as 
the Rhinanthus does not grow in clean earth. Mr. Clarke has 
for some years been trying to raise it from seed in clean earth, but has 
never succeeded. The other method of destroying weeds by green 
crops in rows is equally unsuccessful, as it does not grow among 
green crops. As it is annual, it certainly should be pulled up before 
VOL. V. P 
