July 29, 1899. 
THH GARDENING WORLD 
761 
^ , r- m r ..... —- , 
Thrift Edging. — S. S.: Though this little plant 
soon spreads beyonds the limits we wish it to, yet 
from its hardiness and rapid establishment a new 
planting can be made every year, and two months 
after finishing we may depend on having a brilliant 
rosy-mauve line. Dig the ground along the edge of 
the border, then tread it firmly. Next lay a line 
evenly and tightly all the way along, after which 
draw the rake along to gain a level surface. Having 
succeeded in levelling the soil, being guided by the 
set line, proceed to beat the soil for greater firmness, 
then cut out a small trench for the reception of the 
plants. The line here again is the guide, for the 
cutting must be kept close against it, and on the walk 
side. Lay in the young rooted plants, previously 
broken up from the old plants. Make them firm and 
water them. The planting may also be done with 
trowels, making in this case a double line of 
alternating plants. 
WATER LILIES AT THE CONFERENCE. 
As mentioned in oar report of the conference on 
hybridisation held by the Royal Horticultural 
Society, at Chiswick, on the nth inst., Leopold de 
is purer white, but smaller. N. odorata rubra, N. 
gloriosa, N. pygmaea helvola, and other fine things 
rendered this group a most interesting one. The 
last-named is the smallest Water Lily in cultivation. 
CONFERENCE ON HYBRIDISATION. 
[Continued from page 747.) 
Hybrid Anthuriums. 
Monsieur A. De la Devansaye gave a very short paper 
on the above subject, in which he laid down certain 
laws governing the fertilisation of the genus. 
(1) . That fertilisation is usually effected in the 
genus Anthurium when the flower containing the 
pistil is to be ripened, and that from which the pollen 
is to be brought, have sprung from a different batch 
of seeds. 
(2) . The bringing into use of pollen from a differ¬ 
ent speces of the same tribe (say Spathiphyllum, for 
example) has a beneficial result. Fertilisation is 
assured and variations in the colour of the flower or 
form of the foliage often arise. 
(3) . In spite of good cross-fertilisation, there are 
cases where little or nothing new is seen in the first 
of the twisted race of Teasles, raised by Prof, de Vries 
(Dipsicus sylvestris torsus), and specimens of a cross 
between the twisted and ordinary Teasles. The 
twisted Teasle had had full effect on the hybrid, and 
a better demonstration of the case could not have 
been chosen, for the couple of hybrid stems were 
equally as tortuous as the crooked parent. A similar 
case to the experiment, described by Mr. Bateson, 
was given by Prof, de Vries. The ordinary hairy 
form of Lychnis diurna was crossed with a smooth 
form of L. vespertina which had been discovered. 
The resulting seedlings were at first all hairy, but, 
as in another place proved, the second generation 
split up into smooth and hairy forms, and the 
smooth ones, when isolated and fertilised among 
themselves, retained their glabrous characters; so 
that in not more than four or five generations, new 
and very different forms had been raised. As if to 
prove that the same results might have been 
attained by natural fertilisation, a specimen of a 
hairless form, which was found in Germany half a 
century ago, was shown, and compared with the 
smooth L. vespertina and the hybrid L. diurna 
glabra, proving identical to both. 
Water Lilies at the Chiswick Conference. 
Rothschild, Esq., Gunnersbury House, Acton, W., 
exhibited a magnificent group of hybrid and other 
Water Lilies. The accompanying illustration, pre¬ 
pared from a photograph taken at Chiswick, shows 
the character and style of the group as set up. The 
background consisted of Nicotiana sylvestris, grown 
in pots, a tall species with racemes of loDg, droop¬ 
ing, white flowers. The latter are relatively small 
compared with those of N. affinis, but the plant as a 
whole has a stately and graceful appearance. An 
Award of Merit was accorded it on Tuesday last by 
the R.H.S. 
The tub that is so prominent in the centre 
contains Nymphaea stellata, a light blue species 
from Africa that has the habit of throwing its 
flowers well above the water on stout footstalks. 
By means of a tank in the open air, and covered 
with a wooden lid in winter, Mr. James Hudson, 
the gardener, contrives to grow and flower this in 
the open air. The flat vessels of water contained 
many fine hybrids aDd varieties of various species 
from the splendid collection in the pond at Gunners¬ 
bury House. Nymphaea marliacea albida is the 
largest of all the hardy Water Lilies, and is certainly 
a magnificent and nearly white flower, N. m. alba 
or second generation, and then the experiment is 
usually abandoned forthwith, and the seedlings 
destroyed. But this is a mistake. The disturbance 
caused by crossing sometimes does not appear until 
in the third or fourth generation, so that those 
desirous of variation must needs have patience. If 
a variation should arise in the first crop, few indiv¬ 
iduals will show it. Their seedlings, however, will 
show greater variation up to so much as one half in 
the third generation, and seventy-five or eighty per 
cent in the fourth. It is necessary, however, to make 
careful selection, to fix the variety when it does appear. 
Hybridisation as a means of Pangenetic 
Infection. 
To make Professor Hugo de Vries’s subject clearer 
to the reader let it be understood, as Prof, de Vries 
in opening said, that pangenetic infection means the 
power which plants have of transferring particular 
qualities from one species to another by means of 
crossing. It is promulgated that each cell has an 
individuality of its owd, and the peculiarities of a 
cell are understood to be capable of isolation and 
transmission to allied species. The result of pan¬ 
genetic infection was illustrated by representations 
11 Hybridisation and its Failures,” 
was the subject the Rev. Professor Geo. Henslow, 
M.A., V.M.H., London, had in hand and very ably 
he treated it. He always is a very lucid and plain 
speaker and at Chiswick he was surpassing fine. 
He, in opening asked why it was that some species 
gave fertile seeds and others did not; also how were 
seeds engendered. We studied their origin from its 
manifestations, but we could not after all tell how it 
came to be a seed any more than we knew of electri¬ 
city, and could tell how electricity was made; but 
we were beaten to tell what, after all, electricity really 
was. We get facts and have just to generalise upon 
them. After all that has been said too, we cannot 
get away from the question of what is a species. 
Botanists try to define species in so many terms, but 
for practical men and purposes we want something 
concrete. Here would be a fairly accurate definition 
of species. A species is known by a collection of 
presumably constant characters taken from any or 
all parts of a plant. The difficulty of it all is to 
have opinions at one, as to how many characters 
constitute a species, for at present some botanists are 
content with a few characters, while others like 
many. 
