336 
THE QARDEHIHQ WORLD. 
April 18, 191)3. 
formed in teh leave®, are acted on, by enzymic moisture, or 
ferments,” and become sugar in solution, and as such travels 
to the storing place, and is again turned back into starch. 
Roots, stems or trunks, bulbs and tubers, branches, and even 
the leaves themselves serve as storing places for water, starch, 
sugar, gum, oils, and perfume. So that we may look on plants 
as starch and sugar-makers, or, as the chemist and physiologists 
say, manufacturers of the useful hydro-carbonates, but it isi 
enough for the gardener to look on plants as living machines 
driven by sun-heat and air, to make for us, from elements such 
as water, earth-salts, and carbon dioxide, “ things pleasant to 
the eye and good for food ; in other words, as Grape oi Apple¬ 
making machines, or dower, fruit, and vegetable producers. 
In order to be living manufactories the plants have to do 
the work of engineers, chemists, refiners or distillers, and rec¬ 
tifiers 1 , and they also unconsciously adopt methods of isolation 
or co-operation, advertisement, savings banks, arid the prin¬ 
ciple of exchange or symbiosis, as shown in mycorhizads, and in 
the nitrogen fixing power of the nodules on the roots- of legu¬ 
minous plants. The bulbs of Hyacinth or Crocus show clearly 
their power of saving up the products of growth force, so that 
said savings can, like a deposit bank, be drawn upon in time 
of need! 
It is the same with the pseudo-bulbs of many Orchrds winch 
grow in the wet season, and flower and seed during the dry 
season, instead of “ saving up for a rainy day.” These things 
save up during the genial wet and growing season for a period 
of rest from either cold or drought. The pseudo-bulb is ex¬ 
posed because it grows in. a warm climate, while the true 
tuber or bulb shelters, itself underground because it grows in a 
colder clime. 
Plants like the insect-eaters have reversed the usual order 
of things, and prey on insects- and other small animals. In 
order to do this they adopt, the division of labour principle and 
form sticky hairs- or glands, like Drosera, traps like Diona-ea, 
or jugs and pitchers as in the- case of Nepenthes and Sarra.- 
cenias—all bournes from whence “ no insect traveller returns.” 
The mere formation of tra-ps and pitchers, however, is not 
enough_they must- be baited in some attractive- manner, and 
finally a pepto-nised fluid or secretion must be developed inside 
to enable them to digest and utilise their prey. _ In “ The 
Field ” newspaper for March 28th, p. 533, is an inteiesting 
account of young fishes being caught by the- bladders of Utii- 
cularia. vulgaris in England, and also by another species of 
Utricularia in Ceylon.' These bladders have s-pring valves at 
the openings or “ mouths” of the little pitchers, which act- a-s 
traps and utilise the struggles of the captives in order to push 
or pull them still more securely into the bladders. ihe 
bladder-traps of the Cingalese Utricularia are barely one- 
sixteenth of an inch in length, and still they can capture a 
fish nearly an inch long. Now, a Nepenthes is like a Stock 
Exchange agent or a limited liability company; it does, 
not exactly issue a printed circular or a prospectus 
promising ‘all sorts of good things/ But it- makes a. 
special appeal to its clientele all the same. Inside the run of 
the pitcher, and along tlm fenced-in passage or pathway leading 
up to it, are honey-secreting glands to attract sweet-loving or 
honey-eating flies-, beetles-, cockroaches, e-tc. The fluid actually 
secreted inside the young pitchers is also scented like ripe 
Apples- by malic acid, which further enables the pep sine in 
the- fluid to digest the flies! Formic acid, another potent- aid 
to- a- pitcher plant’s: digestive powers, is yielded by the ants, 
which, as: well as flies, are attracted to the pit-chers m 
search of food. The thing actually goes a- step further, 
a-nd makes it-s honey-loving ca-pt-ives serve as bait tor 
the carrion or flesh-eating flies, so that it has, so to speak, a 
double string to its bow. Indeed, when we observe all the 
apparent forethought of insect-eating and even common climb- 
iim plants, I think some of you will agree with me that there 
is "something very wonderful in what- in our ignorance we call 
instinct, or hereditary reason ; and that plants, even if they do 
not think, still save up the wisdom of their ancestors, and 
appear to act as if they could think and calculate like ourselves 
as to the probable results of what they were doing. 
In conclusion, let us watch the action of a Runner Bean 
towards a movable pole or support. If you sow a Kidney 
Bean, and wait- till it begins to twist round and round, as if 
looking for—or let us say, trying to find—a support, take a tall 
stake and place it- in the ground 12 in. or 15 in. away from 
the twining shoot, as it twists and waves in the air. You 
will soon notice that the tendril goes on twisting, and that 
every gyration brings the shoot nearer and nearer to the 
support. Why it does this no one knows. It may be that 
the growing tip feels a slight rise of temperature on the side 
where the stake is, and is attracted by a force that only the 
most delicate of thermometers could detect. It may be due 
to several other reasons ; whatever it is, the Bean shoot goes 
to the pole as the bee goes to a flower. There is some subtle 
attraction. Now, just as the shoot begins to curl abruptly at 
the growing end, remove the stake and place it 2 ft. away 
from it on the other side. What happens? The Bean again 
gyrates and follows the pole, a-s if it knew well enough that 
the pole had been taken elsewhere ; and you can cany on this 
simple experiment with almost any twining plant with the 
Same results. Plants are most sensitive in their feelings, and 
not only act at- times as if they could think and reason, but 
actually as if they had memory and could see what they are 
doing as well. 
Specialisation of Parasitism. 
A paper was read a-t the: Linnea-n Society on Feb. 19th, by Mr. 
E. S. Salmon, F.L.S., “ On Specialisation of Parasitism in the' 
Erysipha-ceae.” The author began by explaining the term 
“ Biologic Form,” or “ Species,” by instancing two fungi which 
were not distinguishable morphologically, acting in diverse 
fashion on the same host-plants. This phenomenon has been 
known in the Uredineae for some time, but its- discovery in 
the Erysiphaceae was more recent. In the autumn of 1902 
he bad been working in the Laboratory at- Cambridge on the 
biologic form Erysiphe graminis f. Bromi, which, occurring 
on Bromus interruptus, was found to infect fully B. mollis and 
B. tectorum, and induced only weak infection in B. velutinus 
and B. brizaeformis, but none in B. connnutatus. By using 
the Fungus occurring, on B. hordeaceus, infection occurred in 
B. tectorum and B. velutinus, and subinfection of B. brizaefor¬ 
mis. The B. commutatus form was then tried, which proved 
powerless to infect B. mollis or B. interruptus, infected B 
se-calinus and B. velutinus, and sub-infected B. tectorum and Bl 
brizaeormis. None of these three- forms of the Erysiphe was 
able to infect B. arvensis or B. sterilis ; but when the Fungus 
found naturally on B. arvensis was employed, it infected its 
own host, and also B. mollis, while that- form growing on B. 
tectorum infected B. sterilis. In this series of experiments 
300 pots of seedling grasses were inoculated, four to six leave* 
in each pot- Thirteen species of Bromus proved to' he com 
pletely immune against the four forms of the Fungus used, thus 
indicating the existence of four, or probably five, biologu 
forms. 
The author also pursued his researches on the forms o 
Erysiphe graminis on Wheat and on Oats, the result showing 
that, the Wheat-form cannot touch Barley, Rye, or Oats, no 
Agropyrum repens, but it infected Triticum Spelta. The- Oat 
form cannot infect Wheat, Barley, or Rye, but it can, a-ttacl 
other species of Avena. 
Finally, experiments were made on Erysiphe Polygoni fiou 
Trifolium pratense, which proved unable to infect seven otne 
species of Trifolium, but- it always succeeded on its own host 
plant. Species of other Leguminosae, Lotus corniculatu: 
Medicago sativa, Melilotus arvensis, Lupinus luteus, and Pmui 
sativum were also immune. 
Mr. G. Massee and Professor H. Marshall W ard contribute 
some critical remarks. 
