July i, 1891.] 
THE TROPICAL 
AGRICULTURIST. 
31 
caterpillars. What was to check the tendency of the 
numerous enemies of the vegetable kingdom from 
destroying many types of plant life. Years ago it 
was imagined by " some people that the existence 
of thorns and thistles could be best accounted for 
by the theory of the original transgression. But 
botanists knew that this had practically nothing 
to do with the subject. Thorns and thistles were in 
the world long before the creation of man; and if 
people chose to take a too literal view of many things 
in the Bible, they would find themselves in error in- 
stead of in truth. The fact was that both thorns 
and thistles were natural defences against the enemies 
of many kinds of flowering ijlants, belonging to 
various orders all over the world. These defences 
were perhaps most strongly developed in tropical 
countries, where the battle of life was fought more 
keenly and fiercely than in temperate regions. Look, 
said the Doctor, upon the enormous number of 
substances secreted by the leaves, iiems, roots, 
and fruits of plants. Sometimes the plant's defence 
would Ise its prickles or thorns to prevent mammalia 
browsing upon them, and slugs and snails from 
climbing up their stems — such for instance as the 
bramble, whose re-curved hooks also serve the 
purpose of grappling irons to enable the plant to 
climb by. Thorns were sometimes produced as 
stiffened hairs, as for instance in the gooseberry; 
others had stipules converted at the base into the 
same defensive material, as in the acacias. In the 
hawthorn the branch itself was aborted into thorns. 
Reference was made to the thistle, one of the 
finest armed plants aird the most mechanically 
perfect in the whole world. Then, said the Doctor, 
the leaves of some plants were sour, like the 
sorrel 8.nd mountain sorrel, which contained oxalate 
of potash, which was really a poison, and thereby 
prevented slugs from eating the leaves. Some- 
times the leaves were intensely acrid, like the 
buttercup and lords and ladies {Arum maculalnm). 
The buttercup family was intensely poisonous all 
over the world, and he called to their mind how 
they would see in the dry summer time, when all 
the grass was close cropped, clusters of buttercups 
untouched by the cattle. The order of plants to 
which the tobacco belonged secreted poisonous 
materials — indeed, humorously said the lecturer, if 
the tobacco plant were not so it would not have been 
worth smoking. [Laughter.] He reminded them that 
this peculiar order was objectionable to most herb- 
feeding animals, for instance, the tomato and the 
berries of the bitter sweet (Sohtniim chdcamara.) The 
poisonous character of the henbane (Etjcscj/amus) and 
the belladonna, etc., The poppy secreted opium and 
protected itself thereby. Sparrows, he explained, 
would feed upon the flov/ers of the crocus, but they 
would not touch the leaves and rarely the roots. 
The hawthorn, the flowers of the almond tree, and 
the meadow sweet contained prussic acid. Many 
Elants, especially the grasses, protected themselves 
y secreting a vast amount of silica in their skins. 
Other orders, like the crucifer, had both roots and 
leaves intensely pungent, as in the case of the radish, 
mustard and cress, etc. Some were intensely bitter, 
like the ferns, and these latter were seldom eaten 
by any animal. The tannin in the bark of trees pro- 
tected them against the gnawing habits of mammalia, 
and the bitterness of the strychnine in our gentian 
family, several of which were used by medical men 
as tonics, was remarkable. The lecturer then went 
on' to notice that even the perfume and odours of 
plants, such as the leaves of the sweet briar, mint, 
wild thyme, sage, <tc., were more or less protective 
agencies not so much against animals as against the 
smi, for it is a fact that these perfumes kept the 
atmosphere cool, and they might often see sweet 
smelling plants flowering in the scorching sunshine, 
when those plants not so endowed were 
withered by the fervent heat. The Doctor illustrated 
tliese various phenomena by sketches upon the black- 
board, as well as by coloured diagrams. 
PARASITIC FLO WEEING PLANTS. 
Dr. Taylor passed on to another part of his sub- 
ject, and an exceedingly interesting portion, namely, 
•" ""•" '' '~^ ^^^^°^^^™ ' * '"' iiii " *i' ''''^™tww»M»imit' i ii i immn g 
that of the flowering plants, belonging to what he 
called highly exalted orders which got their living 
by preying upon, robbing, and even murdering the 
neighbouring plants. These remarks were illustrated 
by a series of mounted specimens of the broomrapes, 
vvfhich were found in abundance on every common, 
and were only too well known to every farmer from 
their attacks upon his clover field. The collection- 
had been made by Captain Haward, of Little 
Blakenham, and it showed one species of the broom- 
rape attacking fourteen kinds of different flowering 
plants. Vegeta;ble parasitism could be found in every 
stage. Some species only occasionally indulged in 
it ; others, like the broomrape and dodder, could not 
live in any other way. The dodder belonged to the 
order of the convolvolus. If a seed were put in the 
ground, it would develop a couple of small leaves and 
a long, slender, sensitive stem. They might see it 
waving about as though it were trying to feel out for 
something. If it did not find anything, the plant died; 
if it cama into contact witli any succulent plant, 
it climbed it, and develope suckers which fed upon 
their liost in such a manner that the substance 
of the latter was drawn off into its structure. 
When the dodder stem had once got a good hold it 
let go of the earth, and henceforth lived entirely 
upon the plant which it had embraced. The dodder 
killed off thousands of acres of crop plants every 
year. The broomrape sometimes attained a height 
of 18 inches : it had no roots, except one, which 
crept out in search of some adjacent plant until 
it cam.e in contact with it when it fused itself with 
its victim beneath tlie soil. What a great vegetable 
bully it v/as, sometimes five times as large as the 
plant upon which it levied blackmail. The broomrape 
had remnants of its former leaves brown and shri- 
velled that were not used, so that it even did not 
get the carbon from the atmosphere. The mistletoe 
was another parasitic plant. Its home was in Australia, 
where the huge gum trees there sometimes contain 
more mistletoe foliage than their own, but the 
mistletoe did obtain its own carbon. Then there 
were other vegetable murderers, particularly in the 
tropics, that twisted their stems so round other 
trees as to strangle them. It was impossible to 
go into a tropical forest without being painfully 
impressed by the reckless selfishness and craftiness 
of numerous members of the vegetable kingdom. 
In Brazil, one of these Ilianas, or climbing plants, 
was called the murderer, because it actually spread 
out its stem broadly round the tree it climbed by, 
so as to completely encase it, and the living plant 
often supported within its embrace its dead and 
murdered victim. The ivy was also referred to. 
Space forbids us to enumerate other types of plants 
in different parts of the world which illustrated the 
lecturer's theory of the selfishness, craft, and seem- 
ing cruelty of those members of the vegetable world 
v/hich did not get an honest living by theii own roots 
and stems and leaves, but whose existence depended 
upon the ingenious, sagacious, but immoral practice of 
these expedients of craft. — Ipswich 'paper. 
^, 
A New Mineral. — Mr. H. A. Miers in the Mine- 
ralogical Magazine, describes a new mineral, which 
has u.en uan.ed '' SaDguinite." It was observed 
«\i frecimeus of argentine from Chaiiaroillo, and 
ia probably a hexagonal Buipbarseiiite silver, 
allied to proustite. To the naked eye the mineral 
!'i}pcared to be gothite, but examination with the 
mioiosoope revealed iis different character. Ii has 
Insire, like earthy hematite ; colour, broDz.e-red 
by reflected light, and blood-red by trauemitted 
iifht: streak, dark, purplieh brown. No quinti- 
tntive examination was made, on aoaouat of the 
sn^all quantity of materiul ; a qualitative analysis, 
however, showed the presence of silver, arseuio' 
'kDd Biilphur. The physical charaotors as a whole 
prevent the mineral from being referred to 
proustite or xauthoconite, the mineral beiu" nearer 
like the former in its physioal oharaoters. The 
specific gravity and hardness have not been dq. 
termined. — Public Opinion, 
