1888 .] 
Dr A. B. Griffiths on Fungoid Disease. 
409 
is completely destroyed by this reagent ; but the cucumber plant is 
not injured in the least. On the roots of plants Nos. 4 and 5 (see 
previous table) fungal nodules had developed and were visible 
on November 24th and 26th respectively. These growths were 
destroyed by dissolving in the culture solutions ferrous sulphate to 
the extent of 1 gramme in a litre of the solution. It was seen after 
cutting a series of thin sections, by aid of the microtome, staining, 
&c., that the hyphae of this fungus were completely riddled and 
disorganised, while the root-tissues of the cucumber remained un- 
altered. 
This shows, as I have stated elsewhere, that micro-parasitic 
cellulose differs from the cellulose of the higher plants. Most 
probably it is an isomeric modification of ordinary cellulose. 
I have shown in the case of Peronospora infestans and the wheat- 
mildew, that both of these fungoid diseases are destroyed by 
aqueous solutions of ferrous sulphate (see my papers, loc, cit.). 
It will be remembered that I have recommended the use of small 
quantities (J cwt. to the acre) of iron sulphate as a manure for most 
crops {Journal Chemical Society., 1883, 1884, 1885, 1886, 1887), 
and have obtained excellent results. These experiments have been 
repeated by others with similar results. It is a well-known fact 
that the laic of minimum regulates the growth of plants; that is, 
if any one of the essential ingredients in a soil is absent, deficient, 
or not in the proper form for root-absorption, the plants must suffer. 
May it not be the case with Mr Crocker’s cucumber crops of last 
year, — they were diseased; but as soon as he applied the iron 
sulphate, his plants revived and bore excellent fruits. Here are 
Crocker’s own words, written in a letter dated 29th November 
1887 : — “ I planted the present house of cucumbers in the second 
week in August (1887), and have used the iron sulphate, as 
recommended by you. I find no trace of the disease whatever, — 
although the plants were diseased when I first wrote to you. I 
have been able to cut scores of fruits of the most splendid quality 
— and they have been extraordinarily fruitful. It is the first house 
of cucumbers I have grown without disease for at least ten years.” 
In my paper, written in Paris last summer, and published in the 
Chemical Neivs, vol. Ivi. p. 84, a reference will be found concern- 
ing the destruction of micro-vegetable parasites, &c. (by using iron 
