102 THE ORCHID REVIEW. [APRIL, 1912. 
The mosaic character of hybrids is often illustrated in curious ways. A 
hybrid reproduced by self-fertilisation may show a wide amount of diversity 
among the offspring, owing to dissociation of the original specific characters, 
as in the case of Epidendrum kewense, or again by the appearance of 
‘‘ rogues,” as they are called in horticultural practice. Dissociation may 
also occur in other ways. For example, Cypripedium Dauthieri, a form of 
C. Harrisianum, after long culture sported into a striped form, which was 
described by Reichenbach as variety Rossianum. Later on, this again pro- 
duced a chlorotic form, or what is sometimes termed an albino, which was. 
named variety Poggio Gherardo, from its place of origin, and this in turn 
sported to a curious harlequin-coloured form which was called variety Janet 
Ross, after the lady in whose collection it appeared. In another collection 
C. Dauthieri sported into what was called C. Dauthieri var. The Albino, 
while the original C. Harrisianum has sported into a green form called var. 
virescens. It is probable that what is termed “ sporting” generally is due 
to the same cause, for it is usually seen among plants that have a mixed 
ancestry. 
Graft hybrids, of which the curious Cytisus Adami is a familiar example, 
may be regarded as to some extent analagous with sexual hybrids, for they 
arise from new tissue formed at the junction between the stock and scion, 
and are due to blending of the two diverse ancestries. Moreover, dissocia- 
tion of specific character also occurs, though not quite in the same way as is 
seen among sexual hybrids. It may be noted, however, that it has not yet 
been found possible to raise forms identical with graft hybrids by sexual pro- 
cess, but this may arise from mechanical difficulties connected with fertilis- 
ation, for when once united the diverse protoplasms are capable of living 
together. 
The difficulty, sometimes amounting to impossibility, of hybridising 
certain plants arises in many cases from mechanical limitations, as is well 
illustrated by reciprocal crosses. Epiphronitis Veitchii can only be raised 
with Sophronitis as the seed bearer, and although several other generic 
hybrids have been raised with Epidendrum radicans as the pollen parent it 
has never been possible to obtain the reverse cross. Repeated efforts have 
been made to fertilise this Epidendrum with the pollen of Cattleya and 
Lelia, but always without success, and the difficulty is evidently of a 
mechanical nature. 
Mechanical limitations may be of several kinds, and one which is very 
clearly indicated in the behaviour of reciprocal crosses is connected with 
the relative length of the styles of the two parents. 
is not a good pollen parent, because of the short 
Messrs. Charlesworth once showed me a fi 
fertilised with the Sophronitis, 
Sophronitis grandiflora 
pollen tubes it develops. 
pe capsule of a Cattleya 
which had only matured seeds at the apex. 
