ON VARIEGATION IN PLANTS. 
would be attended by chlorosis, or paleness. Variegation has continued to be held as a symptom of 
disease ; neither hare the researches which have been made respecting it been attended with any 
amount of positive information, as to the cause which produces this phenomenon, and especially on the 
nature of the tissues deviating from their habitual colour. The experiments of Knight on the fertiliza- 
tion of a White Chasselas, and a White Frontignan, by a Vine from Syria, led to the opinion that the 
variegation might be the result of hybridation, seeing that plants having variegated leaves were 
obtained by this operation in the instance alluded to. At the present day, when we possess new and 
more ample details on the streaking of flowers, and on the influence which the variously coloured pollen 
exercises in the production of corollas with numerous tints, it would seem still more reasonable to 
believe that the variegation of leaves in plants raised from seed, is indeed a phenomenon of which the 
first cause has its source in fertilization. But it may be remarked that the production of a branch with 
variegated leaves, on an old tree whose leaves are of the usual green, materially invalidates this 
opinion. Even in plants raised from seed, variegation is a phenomenon sometimes so local that it 
appears at first absurd to seek the cause of it beyond the organ or part on which it is present. Take, 
for example, the Oxalis acetosella, on plants of which are sometimes found, among a good number 
of leaves quite green, one or two presenting a beautiful variegation ; that is to say, a yellow reticula- 
tion on all the nerves and veins of the three obcordate folioles. In this case, the phenomenon is 
evidently quite local ; and as we shall, by and by, demonstrate the organic cause of variegation, this 
fact will be established beyond all doubt. 
In 1830, M. Schlechtendal gave a long enumeration of variegated plants — a list of which is of 
considerable interest to horticulturists, since these " sickly " plants have excited, sometimes, a singular 
mania among amateurs which has so often been turned to advantage by the trade. Miller relates, that 
in his time, when the variegated hollies were introduced to England, they excited so great a passion, 
or " rage," that all other plants seemed to be forgotten. We have, ourselves, known an amateur of 
Liege, who was so fond of these variegated hollies, that he left an order in his will to have a collection 
of them planted over his grave, and his heirs have religiously fulfilled his wish. 
M. De Caudolle, who is of opinion that all plants may present variegation, hesitates to class this 
phenomenon among those of physiology. To him, it appears sometimes a capricious monstrosity, allied 
to the reproduction of seed, — to hybridation ; sometimes a resemblance of atavism. According to the 
same author, it would still be a spontaneous production, as in the singular case cited by Hales, and 
since referred to by numerous authors, in which a variegated Jasmine, grafted on a common one, was 
stated to have communicated its variegation to the leaves below the graft, a circumstance which would 
be extraordinary. M. Moretti, cited by M. De Candolle, would appear to have concluded from this 
fact that the variegation is a malady which is capable of being transmitted in all directions in the tree. 
The physiologist of Geneva, in speaking in another place of variegation, only mentions the yellow and 
the white, regarding these colours as original, primitive, and preserved in one part, while the green 
is developed around it. This view is indeed admissable as far as regards these tints, but not for the red 
brown or rusty colour, or even the white, which is found in those varieties of variegated trees which 
horticulturists designate trieolored. On a Euonymus europseus, with leaves margined with white, we 
have seen, it is true, that the youngest leaves, which were scarcely green, were already white at the 
margin, so that this margin quite preserves its original tint, that which it acquired at its first forma- 
tion ; but on the Acer, the Crataegus, &e., where we find red markings, these are of a subsequent 
formation, and do not indicate a primitive tint : it is evidently a colour which has been acquired. 
Moreover, we may add, that on Piper verticOlatum we have seen the leaves developed green, and grow 
to their usual size with that colour ; then, by and by, the nerves turned white, so much so as to present, 
when old, that variegation which we have designated under the name of reticulated variegation. 
M. De Candolle remarks that endogenous plants present pale longitudinal bands parallel to the 
nerves, while exogenous ones have more irregular spots, a circumstance easily explained by the differ- 
ence of the system of nervation in the two great orders of plants. This writer further adds that these 
bands, or these spots, belong to parts in which the chlorophyll is not perfectly developed, either in 
quantity or quality, to be rendered green by the action of the sun. The direct cause of this pheno- 
menon, says this physiologist, is entirely unknown. It is just this cause that we wish to discover. 
We must, however, before detailing our observations, render full justice to the labours of M. Trevi- 
ranus, of Bonn, who, in this investigation, as in many others, has thrown much valuable light on his 
subject. M. Treviranus first remarked that in monocotyledons the variegations form bands parallel to 
the nerves ; in dicotyledons, as in Carduus marianus, the white is produced on the nerves, while, in 
other cases, as in Aucuba japonica, the yellow spots are distributed without order. He also made the 
important observation that sometimes the variegation is visible on the upper face of the leaves, while 
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