

17 
without killing the onion plant. The solution rahe contain one- 
tenth part FSO, to 100 parts of water. It may even be made 
strong as three-twentieths per cent. without _injury to “the plant, but 
anything stronger than this is like to prove injuri 
diseased onions may be watered with this, or, still better, sprayed 
thoroughly. The ground in the vicinity of the affected p 
be watered with advantage a Pace solution; in this way any spores 
which have fallen off will be des 
In addition to its antiseptic pits ties ay sulphate forms a ve 
valuable manure. In a paper published in the Journal of the Chemical 
Society, 1886, Mr. Griffiths has described Ree experiments which all 
d to show the value of this chemical asa m content 
The first plot of ground was not manured; from this he gathered three 
tons of potatoes. The second plot, which was well manured, gave six and 
a half tons ; whilst from a third plot, which was well manu ured in thes sam 
as the second, but with the addition of iron sulphate, he obtained 
is is e experiment out of 
The iron sulphate should.be applied as a top-dressing after the plants 
have been transplanted. About half a hundredweight should be used to 
i ul. 
It has been found that wheat crops grown in fields manured with iron 
sulphate do not suffer with the wheat mildew, and it is very probable 
that if the land be treated in the mamar indicated, potato and onion 
crops would also escape the fungus. * 
Iron sulphate has the further advantage of being very easily obtain- 
able at a very moderate cost. 
Sect. V.—MACROSPORIUM PARASITICUM. 
There is a second fungus found living upon the onion plant. This is 
known as Pek crosporium parasiticum, and it is one of the Pleosporous 
Ascomycete 
his inet is only found upon the onion after it has been attacked 
by the Peronospora, when the leaves are already dead or dying. It does 
not attack the healthy plant. 
Macrosporium belongs to that class of fungi which are ape as 
Saprophytes ; these are “characterised by living upon dead or decayin, 
organic matter. They are unable to effect a foothold upon he healthy 
plant. Hence if the Potts at a can be exterminated, the Macrosporium 
will disappear at the same tim 
e fact that the Moeeibiees is, so to speak, a sequel to the 
won eh > and that with the extermination of the former the latter 
to describe the very complicated 
But a short 


” Au mi remedies er for the onion disease apply with equal force to the 
potato aise e, which is caused by a fungus, Peronospora in crm a — distinet 
from Paronoiporā Sehleidenidhia; but resembling it in its life-histo 
A 52170. B 
