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and Vilmorin ; while among other ‘‘friends from across the sea ” 
were hybridists from Germany, Holland and Switzerland. 
With regard to the main body of our own countrymen who 
attended the conference, it must be said that horticulturists 
were very well represented, but that, with the exception of 
the readers of papers, biologists were few and far between. 
Among papers of interest that were not read at the confer- 
ence, but will appear in the report, the following may be 
mentioned :— 
Prof. L. H. Bailey, ‘‘ Progress of Hybridisation in the United 
States of America.” 
F. Morel, ‘‘ Hybrids of Clematis.” 
P. Chappellier, ‘‘ Essay on the Hybridisation of Déoscorea.” 
Emile Lemoine, ‘‘ Hybrids of the Common and Laciniated 
Persian Lilacs.” 
L. Henry, ‘‘ The Records of Hybridisation Experiments made 
at the Paris Natural History Museum between 1887 and 
1899.” 
Charles T. Druery, ‘‘ Fern Crossing and Hybridising.” 
Dr. Charles Stuart, ‘‘ Hybrids of A@tmedlus, Viola, Acguz- 
legia, &c.” 
During the first day’s proceedings a fine show of hybrid 
plants and intergrafted genera was exhibited in the vinery at 
Chiswick. 
Turning now to the material laid before the conference, it will 
be best to consider details under special headings.! 
I. THE QUESTION OF SPECIES, 
Significance of the Conception.—As the word hybrid ordin- 
arily means the result of a cross between two species, it 
follows almost necessarily that the question of what a species 
is was several times raised. Prof. Henslow was so bold as 
to give a definition, saying that ‘‘ it is known by a collection 
of presumably constant characters taken from any or all parts 
of the plant.” 
It is necessary to have some idea for working purposes, 
but Dr. Masters came rather nearer to the mark when he said 
that the species once considered sacred, to-day practically 
represented the personal opinion of some man who had paid 
special attention to it. 
Mr. Bateson again still clung to the opinion that species were 
often definite, but breeding work alone, he said, could throw 
light upon the subject. He contended that this had already 
shown that under the title of species and varieties ‘‘ whole 
sets of (physiologically) distinct phenomena are confused 
together,” and taking it as proved that species arise from 
discontinuous variations, he gave three instances where the same 
deviation from type was kept up discontinuously, but in three 
different ways :— 
(a) The hairy wild form of A/atthiola zncana from the Isle of 
Wight was crossed with the smooth wallflower variety of 
the stock. 
The offspring fell into two groups, and from the same 
capsule came one hairy and three smooth plants. 
(4) The usual hirsute type of Zychnzs vespertzna and the hair- 
less form cultivated by Prof. Hugo de Vries were bred 
together. 
The offspring were all hairy, but on being left to 
fertilise each other, the second generation gave 
some hairy, some smooth individuals. 
(c) The variations of Azscztella laevigata which occur in 
Switzerland, one with hairs and the other without (con- 
nected by but few intermediate forms), were lastly joined 
together. 
The offspring were glabrous or intermediate in character, 
but as they became adult the latter forms lost all their 
hairs. 
The experiments quoted are some made by Miss E. R. 
Saunders, of Newnham College, Cambridge. 
So-called Species sometimes Wild Hybrids.—The fact that a 
number of so-called species occurring in nature have been re- 
produced by the crossing of other wild species was considered 
by Mr. Rolfe as of interest to systematic botanists, who must 
now recognise wild hybrids and the work of hybridists. 
So-called Species which are Garden Hybrids.—During the 
discussion Mr, Burbidge showed what great confusion had arisen 
1 For a seriatimt account of the papers,see the Gardeners’ Chronicle, 
series 3, xxvi. Nos. 655 and 656 (July 15 and 22), 
NO. 1552, VOL. 60] 
WNALORE 
[JuLy 27, 1899 
through the giving of Latin names to garden hybrids of whose 
origin no record had been kept. Matters would not be im- 
proved, one would fancy, through the practice of some nursery- 
men whom Dr. Masters alluded to in his address, and who, in the 
earlier days of hybridisation, imagined a foreign locality for 
their own productions in order to overcome the prejudice then 
prevalent against hybrids. Mr. Burbidge’s suggestion was to 
give no classical names to hybrids; but if perforce the habit 
must be continued, let such parts of the parents’ names be 
conjoined as would indicate the origin of the new form. In 
his paper M. Lemoine traces the previously obscure 
origin of a lilac by hybridisation experiments; while M. 
Henry suggests that the conference should undertake similar 
work, and mentions a number of plants to begin with whose 
garden history requires elucidation. 
Il. THe Limits or HyBRIDISATION AND CROSS-BREEDING. 
In general.—Mr. Hurst gave statistics showing that up to 
date twenty-seven genera of Orchidez, several belonging to 
different tribes as arranged by the systematic botanists, had been 
connected together by hybridisation. In other families so much 
has not been accomplished, but the same speaker noted five 
species of Rhododendron and four of Gladiolus that had been 
linked together. He said that the breeder might reasonably 
expect to be successful within the limits of a tribe; while, on 
the other hand, it was urged during the conference that an ex- 
periment is easy, and it is better to make it than to argue its 
non-success instead. 
Dr. Wilson, in speaking of his results, said that he had 
hybrids of A/duca, in whose bodies five, if not more, original 
species were combined. 
It can easily be seen that differences in structure may prove 
insurmountable barriers to hybridisation, but constitutional 
differences may often be disregarded. For instance, to quote 
Mr. Hurst, annuals can be crossed with perennials [M. 
de Vilmorin’s poppies], deciduous trees with evergreens [Mr. 
Herbert Webber’s oranges], plants from the tropics with plants 
from within the Arctic circle. 
Special Cases.—Prof. Henslow discussed the question of some 
allied species which unaccountably will not cross, and he 
smilingly pointed out how much trouble would be saved if only 
one could tell plants’ capabilities in the way of hybridisation 
from their outside appearance. Sometimes, he said, species of 
the same genus from different climates and habitats formed no 
hybrids, while even within the limits of a single species the red 
‘“geraniums” (Pelargonium) of France would not cross with 
English races; and certain strains of Primula szmensis, also 
mentioned by Mr. Hurst, and raised by Messrs. Sutton and 
Sons, were not fertile z7zfer se. 
Non-reciprocity.—Though many reciprocal crosses were re- 
corded in the course of the conference, many failures, it was 
pointed out by the last-mentioned speaker, are known, but no 
further light was thrown upon the matter, 
III. Crosstnc A MATTER OF CONDITIONS. 
Some one alluded to the fact that, whereas it might be found _ 
impossible to effect a cross with the earlier produced flowers of 
an inflorescence, say, yet hybrids could be easily obtained from the 
blossoms that opened later. In connection with this, Dr. Wilson’s 
hybrid Passtfora might be mentioned, where the first flowers 
to appear contained coronal rays, or else a second and miniature 
ovary within the walls of the usual one ; but in the case of the 
flowers borne near the ends of branches the pistils were normal. 
The way in which it was again and again reported that a 
hybridising experiment had failed for one, two, three, up to 
seven years shows that successful crossing must depend in a 
great measure upon at present unknown conditions of nutrition, 
acclimatisation, temperature, or something else. 
IV. PREPOTENCY AND THE CHARACTER OF HYBRIDS. 
Non-prepotency of Sex.—Where a hybrid appears to take after 
one parent in the more obvious and striking parts of its organisa- 
tion it may resemble the other in more hidden but not less im- 
portant characters (Mr. Hurst and M. Mael). Again, when 
species A, on being crossed with species B, produces hybrids that 
are practically replicas of itself (‘‘ false hybrids” of Millardet), it 
does not follow that the prepotent species, A, must necessarily be 
male or necessarily female (Henslow). Furthermore, reciprocal 
hybrids may be identical. 
