16 
THE AUSTRALIAN GARDENER’ 
SEPTEMBER I, 1902 
applied to the “living together” of various 
organisms when each assists the other, not 
parasitism, but “chumming.” The most 
important case is that of Lichens. These 
are now generally admitted to be alge and 
fungi living together. The alge are 
“groups and filaments of round, ellipsoi- 
dal, or discoid green cells,” and the fungi 
“pale, tubular cells, destitute of chloro- 
phyll,” the algal cells being’ interwoven 
with the filaments of the fungus. 
Another case of symbiosis is where the 
mycelium, or web, of a fungus grows over 
the root fibres of a flowering plant, and by 
absorbing water and its contained salts, 
helps to feed the shrub or tree. Some 
plants, such as Heaths, Daphnes, and 
Rhecdodendrons, seem to be dependant 
upon these fungi, and do no propagate if 
the roots are cleared of the fungoid mantle. 
Limes, Roses, Ivy, and Pinks, which are 
free from the fungus, can be propagated in 
damp sand; but oaks, beeches, heath, 
brooms, &c., whose roots have a mycelial 
mantle, will not continue to grow from 
cuttings in sand. If, however, the sand 
contains humus just taken from a heath, 
the cuttings will sometimes grow, the 
humus probably containing germs of the 
fungus. The fungus benefits by absorb- 
ing the juices of the tree. “The range of 
species which live in a social union such 
as is here described is certainly very 
large.” 
The tree appears to have some choice as 
to its companion, for the Japanese 
Sophora and the Australian Epacridae, are 
found in European gardens in social union 
with native fungi which certainly do not 
occur in Japan or Australia” respectively. 
But the presence of ai mycelium envelop- 
ing the roots of a flowering plant is not in 
all cases a proof of symbiosis. Thus Mono- 
tropa allied to the Primrose bears no green 
leaves, and in general possesses no trace of 
chicrovhyll, and derives its nourishment 
from the fungus surrounding its roots; but 
the fungus does not penetrate the roots, 
so that it is not symbiosis, but the flower- 
ing plant is a parasite on the fungus. 
Sometimes this symbiosis is of a more 
complex character: thus the greater part 
of the absorption roots of the Black Poplar 
are covered by a dense mycelial mantle, 
but where they are free they are taken pos- 
session of by the suckers of a Toothwort, 
and in the leaves of this (as already noted) 
are housed various small animals, such as 
Rotifers. Or the Poplar bears parasitic 
Mistletoe, and the Mistletoe is covered 
with Lichens, which again, as we have 
learned, are a community of algae and 
fungi. Reckoning the mosses, lichen, 
liver-worts, galls, beetles, butterflies, &c... 
living on a poplar, the number, according 
to Kerner, “is not much fewer than fifty.” 
Under the heading “Conduction of 
Food” the very difficult question of the 
ascent of sap to the tops of the highest 
trees is entered upon. “Capillarity” was 
first pressed into the service as an ex- 
planation, but the vessels of the stem and 
leaves are closed above and below, and at 
hest capillarity could only raise the fluid 
a short distance. Then “Osmosis” was 
suggested—that is, the transpiration of 
fluid through the walls of the cell, these 
walls being so built up that the fluid 
would pass more readily in one direction 
than another, i.e, upwards more easily 
than downwards. Again, atmospheric 
pressure was made use of as an explanar 
tion, but with a perfect vacuum in the 
upper part of the tree the water could 
only rise about 30 ft. Then transpiration 
was brought in: by evaporation the con- 
tents of the upper cells become more con- 
cextrated and draw upon the next lower 
cells for fluid supply, these in turn upon 
those below them, and so on to the ab- 
sorptive root. 
- However produced the quantity of sap in 
movement in a plant is very great. “In 
Java certain lianes are made use of as vege- 
table springs. The watery sap flows so 
abundantly from a cut branch that in a 
very short time it will fill a glass, and 
forms a cool and refreshing beverage.” 
Even from a Rose more than 2 lb. weight 
of sap was exuded in a week. . 
Transpiration chiefly occurs through the 
leaves by means of numerous small open- 
ings called “stomata.” These openings 
vary in size according to the dryness of 
the air, being opened or closed by a pair 
of kidney-shaped cells situated on the rim 
of the opening. It is evident that the 
_ moister the air the more difficult it is for 
plants to part with their excess of fluid, 
therefore, in the damp tropics we find the 
largest leaves. Thus the leaf blades of 
the Corypha palm of Ceylon are eight 
yards long and six yards wide. In 
Brazil the petiole of the Raphia palm is 
five yards long, and the blade 22 yards 
long and 12 yards wide—the largest leaf 
known. If such a leaf were propped up 
against a house it would reach 80 ft. in 
height, or half the height of the Post 
Office! As the stomata are invisible to 
the naked eye, imagine the countless mil- 
lions on one such leaf! 
(To be Continued.) 
SPRAYING IN BLOOM. 
— OoO——— 
[From ‘Experiment Station Record,’ Washington ] 
The practice of spraying fruit trees in 
bloom, as begun a few years ago, has led to 
considerable controversy as to the effect of 
such treatment upon the yield of fruit, as 
well as the injury to bees. As a result of 
the agitation a law was passed by the legis- 
lature of the State of New York prohibiting 
the application of poisons to fruit trees while 
in blossom. The effect of such treatment 
upon the production of fruit has been in- 
vestigated at both the New York State 
Station and the New York Cornell Station. 
During the year 1900 extensive field experi- 
ments were conducted by the Cornell Sta- 
tion on spraying fruit trees in bloom, which 
showed no decisive results. The season was 
one of heavy crop and little disease, and good 
or fair crops followed all treatments. ‘There 
was no apparent injury to blossoms on trees 
sprayed when in full bloom, 
The effect of spray mixtures on pollen and 
blossoms was studied by the State station 
both in the laboratory and in the orchard. 
In the laboratory, pollen grains were put into 
culture which contained insecticides, or fun- 
gicides, and the germination and growth 
compared with others placed in culture media 
without any fungicide or insecticide. “‘ From 
these ivestigations it appears that if before 
pollination occurs ‘the stigmatic surface of 
the pistil should be covered either with 
Bordeaux mixture alone or with arsenical : 
poison alone, of the strength commonly used 
in spraying orchards, there would be no 
germination of any pollen which might after- 
wards reach the stigmatic surface, and so 
fertilization would be prevented and no fruit 
would be formed. Even the presence of 
lime alone, of the strength commonly used 
in spray mixtures, prevented the germination 
of pollen. Bordeaux mixture was diluted in 
aqueous sugar solution to 500 parts, 200 parts, 
100 parts, 50 parts, 2 parts, and 1 part in 10,000 
of culture media into which various kinds of 
pollen were introduced. Even when diluted 
. to 50 parts in 10,000 it prevented ‘germina- 
tion to large extent, and where germination 
did occur the growth which followed was 
decidedly slow, and the pollen tubes were 
dwarfed. Whendiluted to rooparts, 200 parts, 
or 500 parts either no germination or practi- 
cally none was found.” 
The effect of spray mixtures on the apple 
blossoms was examined, trees being sprayed 
in bloom and observations made at different 
times until the fruit had become as large as 
cherries. In the tests where the trees were 
sprayed repeatedly, so as to hit as many as 
possible of the new blossoms which opened 
from day to day, but few blossoms survived 
the treatment and but little fruit was set, 
showing that spray mixtures prevent the 
setting of fruit when applied to blossoms 
soon after they open. If the tree should 
have a scant amount of blossoms, serious 
loss might follow from such treatments. In 
some cases the spray mixture had a decided 
corrosive effecton the tissue of the stamensand 
pistils. In other cases pistils which showed the 
presence of spray mixture on the. stigmatic 
surfaces awaited fertilization for several days, 
but eventually withered and died. It appeared 
that in these cases the spray mixture pre- 
vented the process of fertilization. Blossoms 
which had been opened several days before 
being sprayed seemed to have reached 
a stage where the treatment did 
not -check fertilization, and the fruit 
fruit was set as abundantly as upon those 
trees which were not sprayed. The effect of 
spraying in bloom upon the yield was investi- 
gated with a number of varieties of apples. 
In the case of Hubbardston the loss per tree 
from spraying in bloom was 0.9 bu. of 
marketable fruit ; with Oldenburg and Bald- 
win the loss was 0.4 bu.; with Tompkins 
King, 1% bu., and with Rhode Island green- 
ing 1% bu. . In some cases the spraying 
in bloom thinned the fruit, and the thinning 
done seemed to produce results somewhat 
similar to those produced when the young 
fruit is thinned by hand, that is, the total 
yield is slightly decreased, but the amount of 
marketable fruit is not in any way diminished. 
Other experiments gave contradictory results, 
and further tests are needed to establish a 
safe general conclusion on this point, 
