February 19, 1885 ] 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
157 
the explanation of this phenomenon, which my observations gave rise to 
as described in my “ Visit to South America,” 1878. The peculiar 
characteristics of these vast level plains, which descend from the Andes to 
the great river basin in unbroken monotony, are the absence of rivers or 
water-storage, and the periodical occurrence of droughts, or “ siccos,” in 
the summer months. These conditions determine the singular character 
both of its flora and fauna. The soil is naturally fertile and favourable 
for the growth of trees, and they grow luxuriantly wherever they are pro¬ 
tected. The Eucalyptus is covering large tracts wherever it is enclosed, 
and Willows, Poplars, and the Fig surround every estancia when fenced 
in. The open plains are covered with droves of horses and cattle, and 
overrun by numberless wild rodents, the original tenants of the Pampas. 
During the long periods of drought which are so great a scourge to the 
country, these animals are starved by thousands, destroying, in their 
efforts to live, every vestige of vegetation. In one of these siccos, at the 
time of my visit, no less than 50,000 head of oxen and sheep and horses 
perished from starvation and thirst, after tearing deep out of the soil every 
trace of vegetation, including the wiry roots of the Pampas Grass. Under 
euch circumstances the existence of an unprotected tree is impossible. 
The only plants that hold their own, in addition to the indestructible 
Thistle, grasses, and Clover, are a little herbaceous Oxalis, producing 
viviparous buds of extraordinary vitality, a few poisonous species, such as 
the Hemlock, and a few tough thorny dwarf Acacias and wiry rushes, 
which even a starving rat refuses. Although the cattle are a modern 
Fig. 28.—Sollya linearis. 
introduction, the numberless indigenous rodents must always have effec¬ 
tually prevented the introduction of any other species of plants, large 
tracts are still honeycombed by the ubiquitous biscacho, a gigantic rabbit, 
and numerous other rodents still exist, including rats and mice, Pampas 
hares, and the great nutria and carpincho on the river banks. That the 
dearth of plants is not due to the unsuitability of the subtropical species of 
the neighbouring zones cannot hold good with respect to the fertile valleys 
of the Andes beyond Mendoza, where a magnificent hardy flora is found. 
Moreover, the extensive introduction of European plants which has taken 
nlace throughout the country has added nothing to the botany of the 
Pampas beyond a few species that are unassailable by cattle, such as the 
two species of Thistle which are invading large districts, in spite of their 
constant destruction by the fires which always accompany the siccos.— 
Edwin Clabk (in Nature ). 
SOLLYA LINEARIS. 
The attractive little plant represented in the annexed engraving is 
the prettiest of the few species constituting the genus Sollya. Like its 
relatives S. heterophylla and S. Drummondii it is a native of Australia, 
whence it was introduced about forty years ago. In habit it is slender 
and scandent, with linear bright green leaves and very numerous deep 
blue pendulous flowers, which are succeeded by long seed pods that 
remain on the plant for a con.-id arable time. The plant is easily culti¬ 
vated, and when trained over a pyramidal trellis, as we recently saw a 
specimen in the temperate house at Kew, it is really charming. It 
thrives in a greenhouse temperature either in pots or planted out, and 
requires a soil composed of loam and peat with an admixture of sand, 
or the peat may be omitted. 
ROYAL HORTICULTURAL SOCIETY. 
Scientific Committee. —Present: Sir J. D. Hooker in the chair ; and 
Messrs. Grote, Beddome, A. Michael, Pascoe, Smee, Murray, Ridley, Masters, 
Llewellyn, Loder, and Wilson. 
Sclerotioids in Potatoes. —The following communication was received 
from Professor Traill, who had used various re-agents in testing the nature 
of these bodies, as suggested by Professor Foster at the last meeting :— 
“ Since I wrote in the month of January in regard to the result of my 
experiments on the sclerotioids in the leaves of diseased Potatoes, using for 
these experiments material given me by Mr. A. Stephen Wilson, I have 
continued and extended my observations. I have made use of several 
additional tests, and have found the results yielded by them confirm the 
conclusion that the bodies in question are masses of protoplasm coated with 
a deposit of oxalate of lime. As the subject is of much practical interest 
in its bearing on the propagation of disease in the Potato plants I subjoin 
a description of the results of the tests employed by me in addition to those 
previously mentioned. The former tests were also repeated, and gave quite 
the same results as they had done previously. 
“ In every case, except where specified, the bodies were teased from 
among the tissues in which they lay imbedded, so as to allow of certainty 
that the same body remained under observation during the whole course of 
operations to which it was subjected ; nitric acid was then added in sufficient 
amount to dissolve the oxalate of lime, and the excess of acid was carefully 
washed away before any other re-agent was addffi. In every case whe e 
the body was so isolated, and where care was taken to prevent its escape 
from the field of the microscope, there remained a nearly transparent finely 
granular body, as described in my former communication. Nor was it 
difficult after the situation of the body had been carefully noted with re¬ 
lation to the surrounding objects to detect it again after the slide had bem 
moved and the body was again brought into the field of vision ; but where 
such care had not been taken it was frequently very difficult to rediscover 
it, and it is easy to understand how one might suppose that nothing re¬ 
mained after the action of nitric acid. 
“ The residuum, as I shall call what remains after the removal of the 
oxalate, retains nearly the size and form of the entire sclerotioid ; but no 
true cell-wall can be detected even with the most careful examination— i.e., 
no cell-wall separable from the rest of the mass. Yet, as the mass retains 
its form in water and in other fluids, and resumes its form after moderate 
pressure has been made on the cover glass, the outer surface, like a primor¬ 
dial utricle, must serve as a wall. 
“ The residuum is faintly yellowish, and on running in dilute solution 
of ammonia this colour becomes slightly deepened ; dilute ammonia did not 
dissolve the mass. 
“ Dilute potassic hydrate did not markedly alter the appearance of entire 
sclerotioids, but it dissolved the residuum more or less. 
“Acetic acid, osmic acid, and chromic acid all rendered the residuum in 
some degree more visible, diminishing its transparency. Osmic acid 
changed the colour slightly ; and chromic acid rendered it yellower. 
“ On running in a solution of iodine and potassic iodide the residuum 
became pale brown or yellowish-brown, being render d very much more easily 
detected, though not so dark as the contents of the Potato leaf cells. 
“Solutions of saffranine and of aniline blue stained the residuum, though 
less dark than the cell contents of the leaf tissues. 
“ Picrocarmine had little effect on either the residuum or the leaf cells, 
but it is not of general use in vegetable histology.— James W. H. Traill.” 
Mr. G. Murray, having independently examined these bodies, reported 
as follows :— 
“ I have to report to the Committee than in compliance with its reference 
to me on the subject, I have renewed my inquiry into the nature of the 
bodies which Mr. Stephen Wilson calls ‘ sclerotiets ’ of the Potato disease. 
It will be remembered that the result of my previous examination of these 
bodies was the discovery that they consist of oxalate of lime, and my opinion 
was (and, it may be said, still is) that they are intrinsic products of the 
Potato plant. Since that was announced Mr. Wilson has again address. d 
the Committee on the subject. He accepts the oxalate of lime, but states 
that in addition to it there is present a substance which he asserts is proto¬ 
plasm; and this he regards as establishing again his views as to the con¬ 
nection of the bodies in question with Phytophthora infestans. Professor 
Traill has also sent you a report in which he states that, after dissolving 
the oxalate of lime, a substance is left which may be stained with magenta. 
He also judges this to be protoplasm. 
“Mr. Worthington Smith, working independently, has made the same 
observation, and has furnished figures illustrating the aspect of the objects. 
His contention is that we have here a central mass of protoplasm encrusted 
with oxalate of lime. In this view I shall join with him Mr. Wilson, and 
also Professor Traill, who has ‘no doubt that the sclerotioids are masses of 
protoplasm coated with calcium oxalate, probably in the form of minute 
raphides.’ 
“ But for this unanimous statement that the substance in question was 
contained in the oxalate of lime, the appearance might have been explained 
without further investigation. However, I proceeded to carefully repeat 
these experiments with the bodies strictly isolated from the tissues, and 
giving a clear, definite outline, precisely as described by the above observers. 
After treatment with dilute nitric acid there was no difficulty in finding the 
substance referred to, and none in repeating the staining process, but I 
failed entirely and absolutely to find the smallest evidence that this sub¬ 
stance was contained in the body. The statement that it is so contained is 
the merest assertion. Obviously if it were the case it would suit Mr. 
Wilson’s theory. If the protoplasm were outside it is equally obvious it 
would bear out my interpretation. I can prove that it is so. In order to 
demonstrate the presence of this substance, it is not necessary to remove the 
oxalate of lime with nitric acid. The observer has only to isolate as well as 
he can one of these bodies, and apply iodine, for example, to obtain the 
desired stain. This will appear as a delicate colouring, and not with the 
intensity that would result were the whole mass to take up the stain. This 
