October 7,1880. ] JOURNAL OF HORTICULTURE AND COTTAGE GARDENER . 383 
binata he found to contain two substances, to which he gives the 
names “droserin” and “azerin.” Dr. Tait confirms Sir J. D. 
Hooker’s statement that the fluid removed from the living pitcher 
of Nepenthes into a glass vessel does not digest. A series of 
experiments led him to the conclusion that the acid must resemble 
lactic acid, at least in some of its properties. The glands in the 
pitchers of Nepenthes he states to be quite analogous to the peptic 
follicles of the human stomach, and when the process of digestion 
is conducted with albumen the products are exactly the same as 
when pepsine is engaged. The results give the same reactions 
with reagents, especially the characteristic violet with oxide of 
copper and potash, and there can be no doubt that they are 
peptones.— {Nature.') 
THE POTATO DISEASE. 
In a previous communication I stated that the disease was due 
to a rupture of some of the organs by a glut of rain during some 
period of the plant’s growth, and that this was capable of proof. 
I now give some methods of proof convincing to my mind. 
1, After heavy rains attended by a muggy densely saturated atmo¬ 
sphere, examine microscopically all the parts of the plant at any 
stage of its growth, and many of the cells will be found ruptured. 
2, Gather from reliable sources the results of growing Potatoes 
under glass, and where they are free from excessive moisture, and 
the evidence will show the absence of disease. 3, Securely fix a 
large light over a portion of your patch of Potatoes, so that the 
surrounding conditions of growth shall be felt beneath, but that 
the rain shall be thrown on those growing near; and if the season 
be at all wet the sheltered Potatoes will be sound while those 
receiving the extra rain will be diseased. 
The state of the Potato crops this season is another proof, at 
least to me. This year the heaviest rainfall has been somewhat 
limited to the western and midland counties, and, so far as I know, 
in these counties only have the Potato crops suffered severely, 
particularly so where the land is heavy and ill-drained. A friend 
in Fifeshire tells me his crops are very heavy and quite sound. 
The rainfall there in June, July, and August has been considerably 
less than in the Yale of Gloucester where the disease prevails largely. 
Similar experiences induce me to suggest that you invite qualified 
correspondents in selected localities to give you the rainfall from 
May to August inclusive, and the state of the Potato crops in 
their districts. The evidence of these facts will most certainly 
prove that where an excessive rainfall has occurred, there the 
disease has prevailed — modified of course by soil, drainage, 
varieties, and culture. 
These facts have convinced me that wet seasons and not fungus 
cause the disease. It may well be that what is superabundant 
moisture to the Potato is a condition suitable to the growth 
of fungus ; what is disease to the one is vigorous health to the 
other, but still excessive moisture is the cause of the disease, and 
fungus is a result. 
It will be interesting to know if others have followed this line 
of thought and experiment, and with what results. The import¬ 
ance of the subject is worth the attention of the Meteorological 
Office and the authorities of Kew Gardens. I do not think we 
can conquer the disease, because we cannot order the seasons, but 
we can do much to limit its ravages by cultural directions. Those 
which I have successfully practised shall be sent to you for another 
issue.—A n Interloper. 
I DO not know whether your readers are tiled of this subject, 
but I am like the “ Song of the Brook,” I could go on for ever. 
It is a subject which interests me and to which I have devoted 
considerable time. I see “Lincolnshire Potato Grower” 
says that I have not contradicted his statement that nine- 
tenths of my book is composed of the experience of others. 
With regard to this, some years ago I wrote a series of articles in 
this Journal, in which I treated of the disease from a purely 
theoretical point of view without referring to the writings of 
others at all. Now those articles were criticised, and were found 
fault with because I had not referred to the writings of others. 
So much for critics. At the same time I admit that my former 
critic would have been right if it had been a general treatise on the 
disease, which the book is ; and for anyone to write a treatise of 
that nature entirely from his own experience, and without refer¬ 
ring to the writings of others, in my opinion would be a great 
mistake, and the book would not be worth reading. It would be 
like the play of Hamlet with Hamlet left out. 
Then, again, he says it is not a practical book at all. With 
regard to this I entirely differ from him. It is full of practical 
information from beginning to end. Again he says, “ Pulling the 
tops off has been of great benefit, and this is not mentioned,” but 
on referring to page 57 and reading it over carefully anyone may 
see that it is. 
Then again he says, “ Neither is the theoretical plan for the 
extinction of the disease of any practical value, at least according 
to the authority of Mr. Worthington Smith.” Oh yes ! we are to 
sit back in our chairs, fold our arms, and look complacently on as 
we have been doing for the last thirty-five years ! When railways 
were first invented, letters used to be written by scientific men to 
various journals saying that it was impossible for any railway 
train to travel at the rate of sixty miles an hour in consequence 
of the resistance offered by the pressure of the atmosphere ; but 
that we all know was found to be erroneous. Now let us examine 
some of the statements quoted from Mr. Smith :—>■“ If Potatoes 
were taken into an island in the middle of the South Pacific, or 
transported for miles upwards into the air, or submerged for years 
in a river, they would yet be liable to contamination from the 
Peronospora, for the spores of the fungus are everywhere. Spores 
are present everywhere, and can no doubt be carried through the 
air across a sea or ocean as readily as over a hedge. Spores 
everywhere sail with the wind and at the same speed. Nothing 
is better known than the descent of spores, pollen, and other 
minute organisms on to ships in mid ocean.” The spores of the 
fungus do spread about there is no doubt, but the remarks of Mr. 
Smith are much too sweeping. Instead of an island in the South 
Pacific let us fix on one in the South Atlantic—viz., Tristan 
d’Acunha. This island, as some of your readers know, is about 
half way between the Cape of Good Hope and the Argentine 
Republic in South America. Now Potatoes have been grown on 
this island for more than twenty years without any sign of disease 
whatever, so that it is very evident they are safe from the spores 
notwithstanding what Mr. Smith says; and with regard to the 
Isle of Man, in my opinion the result would be the same if 
the island were once cleared of the disease. Other people may 
differ from me in opinion, but the question can only be satisfac¬ 
torily decided by putting it to the test of practical experience, 
which I am glad to say is being done in Argyleshire.— The 
Writer of the Book. 
TREES AND SHRUBS FOR PLANTING NEAR THE 
SEA. 
In response to Mr. B. Cowan’s query, I have noticed the greater 
portion of the undermentioned flourishing near the sea and not 
far from both tin-smelting works and a tanyard. Plants and 
trees that will thrive in such places will probably succeed with Mr. 
Cowan. Trees .—Cedrus Deodara, Acer pseudo-platanus, Ailanthus 
glandulosa, Cratmgus oxyacantha, Hippophae rhamnoides, H. con- 
ferta, Ilex aquifolium, Pinus Cembra, P. insignis, P. Pinea, P. 
Pinaster, P. Strobus, Pyrus Aria, Quercus coccinea, Q. Cerris, 
Q. Ilex, Q. robur, Tamarix gallica, T. germanica, Tilia europasa, 
Ulmus nigra, U. rubra. U. stricta. Shrubs .—Aucuba japonica, 
Berberis aquifolia, B. Darwinii, B. fascicularis, B. vulgaris, Ar¬ 
butus procera, Escallonia macrantha, E. Ingrami; Euonymus, 
silver, golden, and the common green-leaved varieties, the latter 
is the best; Syringa persica, Ligustrum japonicum, Sambucus 
nigra, S. racemosus, Garrya elliptica, and the fine ornamental 
Grass Gynerium argenteum. Should I notice any others I will 
not fail to communicate their names. I confess I am unable to 
answer Mr. Cowan when he asks, “ Can it be explained why Elders 
withstand the effect of chemicals ?”— W. Roberts, Penzance. 
THE MOULD OR FUNGI ON THE HOP PLANT, 
PEACH TREES, POTATOES, AND GRAPES. 
I HAVE this year had an opportunity of seeing and carefully 
examining the disease called the Mould in the Hops, having visited 
several of the Hop gardens in Kent; and from inquiries made 
both of the masters and men employed in the cultivation of Hops, 
I have come to the conclusion that the mould is caused by the 
sun. When the Hop is in full bloom, if a shower of rain is fol¬ 
lowed by scorching heat, the very abundant pollen, which has 
already been rendered wet, becomes baked on the plant, and the 
fungus is then produced. Many facts bear this out. First, the 
Hops, I am told, looked well and gave the farmers hopes of a 
good crop up to the time of their coming into bloom, and the 
mischief was not perceived till a week or two afterwards, when 
the fungus had begun its destroying work. Being caused by the 
climate, 1 am afraid the fungus cannot be prevented. By planting 
different varieties of Hops so as not to have them all in bloom, 
the risk of loss would, I think, be less than it is now. 
The blister on the Peach trees I think might be traced to the 
same cause. 1 have found trees that have been lilted and replanted 
have been the worst affected. The trees were on a south wall 
