affecting tlie Corn-Crops. 
513 
me wliich had been sown, and had made shoots from half to an 
inch in length, when they died, owing, it was believed, to their 
being infested by a Millipede, called Polydesnms complanatus, 
which was lately figfured and described in this Journal.* There 
was every appearance of their being the culprits, for they swarmed 
round the grains, which were much injured, and fast decaying; 
the only question is, whether they fed upon the grain before or 
after it became in a sickly state. 
Vibrio Tritici. 
Although neither the Millipedes nor the Vibrio belong to the 
same Class, they are so intimately connected with Insects, in 
aflfecting the crops, that I could hardly complete mv subject if I 
did not include them in this Essay ; and as it is many years since 
the history of the Vibrio was published in the ' Philosophical 
Transactions,'t and that work may be inaccessible to many agri- 
culturists, I am induced to introduce sketches to illustrate its eco- 
nomy from the inimitable drawings of the late Mr. Francis Bauer, 
deposited in the Banksian Library of the British Museum, and 
they will prove the more acceptable from Professor Henslow having 
included the Vibrio in his ' Report on the Diseases of Wheat ' in 
a recent volume of this Journal.J; 
The minute worm which causes the disease called ear-cockle, or 
purples, belongs to the Class Infusoria, and has been named 
17. Vibrio Tritici. The eggs are taken up by the sap from the 
infected grain which may have been planted, and hatch in the stalk § 
as well as in the germen. The largest worms (fig. 28) are a 
quarter of an inch long at least, of a yellowish-white colour, and 
not so transparent as the young worms (fig. 27) ; " their heads are 
very distinct ; they have a kind of proboscis, which has three or 
four joints, which they contract or extend like an opera-glass. 
From the head, which is somewhat roundish, they taper gradually 
oft" towards the tail, which is scarcely half the diameter of the 
middle of their body, and ends in an obtuse claw-like point. At 
a short distance from the end of the tail is an orifice, surrounded 
by an elevated fleshy edge ; from this orifice the worms discharge 
their eggs (fig. 29). The back of these old worms is nearly opaque, 
and appears jointed or annular ; the number of joints or rings is 
from 25 to 30; the belly side is more transparent, and strings of 
* Royal Agric. Jour., vol. v. p. 230, pi. J, fig. 55. 
t The Croonian Lecture, read before the Royal Society, Dec. 5, 1822, 
and published in 1823, in their Transactions, vol. i., p. 113, being ' Micro- 
scopical Observations on the Suspension of the Muscular Motion of the 
Vibrio Tritici; by Francis Bauer, Esq., F.R., L.S. &H.S. 
X Royal Agr. Jour., vol. ii. p. 19. 
§ Ml-. Bauer thinks this may be another species of Vibrio. 
