CURRENT LITERATURE. 213
Plant disease
Blakeslee, A. F. A graft infectious disease resembling a vegetative mutation. Jour, of Gentics II. 1st April, 1921.
In this paper is described a disease of Datura stramonium which causes profound changes in leaf, flower and fruit. The leaves become narower and incised, the corolla is split down to the base and frequently fails to become free of the calyx, the stamens are devoid of pollen, the capsules are less spiny or quite smooth, and the colour of the plant is usually darker. The disease appears in the field to the extent of about 16 % of all the plants, but up to 26% in an experimental plot where the plants were more widely spaced. This the author thinks was due to the plants growing larger and therefore having a larger area liable to infection. It is transmitted by seed produced by healthy pollen to the extent of about 79%, the remaining 21% of plants raised from diseased stock being entirely free from it. It is transmitted by pollen, that is when pollen is used from normal or nearly normal flowers of plants that are beginning to show the disease, and lastly it is transmitted by grafting: a diseased branch used as scion will affect a healthy stock and even a healthy scion grafted on to the same healthy stock.
It is suggested that vegetative segration and mosaic inheritance in other plants may sometimes be due to some such disease. To the writer of this abstract it appears possible that this disease is similar to the spike-disease of Sandal and other plants in this country, which so far have been studied only on the physiological side, not as far as he knows genetically.
P. F. F.
Plant-breeding, Heredity, etc.
Batcson, W. Root-cuttings and chimaeras II Jour, of Genetics. II., 1st April, 1921.
The author continues his investigation into the product of root-cuttings of certain variegated cultivated plants, of Bouvardia, Pelargonium, and Spiraea ulmaria. In these plants there appears to be a core of one kind over- laid by a cortex of another, the latter giving the varietal character of the plant. Many such herbaceous plants are liable to give rise by root-cuttings to shoots composed entirely of either their external or their internal constituent. Such shoots are probably formed by adventitious buds, which clearly are not always endogenous, but may arise from the cortical layer. The instance of a core character appearing in patches on a leaf are difficult to explain, the growing point apparently has both elements in it.
Kefering to " reversal," described in Vol. IV (see this journal Vol. I, p. 63) while several instances have been seen of white-over-green turning to green- over-white, none have been found of the oposite.
P. F. F.
Rangaswami Aiyangar, G. N. Some rice breeding experiences. Agri. Jour. India, XVI, 2nd March, 1921.
The author who has been for several years engaged in breeding varieties of rice with, F. R. Parnell, gives here some of his experiences and much sound
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