NOTES AND ABSTRACTS. 
497 
Ivel and Ouse, was examined. The author has followed Hall and Russell [" Agri- 
culture of Soils in Kent, Surrey, and Sussex "] in using the geological formation to 
mark the extent of series of soils having a somewhat similar mineral structure, 
the members of each series being differentiated by their varying agricultural 
properties. Thus the seven geological formations met with give rise to seven 
series, each of which furnishes one to three different types of soil, some differing 
in colour, others in texture. There was a notable uniformity of properties in 
the soils thus classified. For example, three analyses of clay loams derived 
from the Oxford Clay formation show coarse sand from 20 to 23*3 per cent., 
clay 19-7 to 2i-2 per cent., K 2 0 -74 to -76 per cent., P2O5 -08 to "ig per cent. 
The clay loams are distinguished from the other Oxford Clay derivative, namely 
the pure clay soils, by containing about 9 per cent, less clay. Both derivatives 
are distinguished from all the other clay soils dealt with in the paper by extremely 
low percentages of calcium carbonate and of phosphoric acid. In a similar 
way there are two derivatives of the Greensand formation, namely dark sands 
and brown sands. Each of these contains 51 to 59 per cent, of coarse sand, 
8-7 to 1 1 -8 per cent, of A1 2 0 3 and Fe 2 0 3 , and -06 to -09 of CaC0 3 , but the dark 
sands contain only about half the percentages of potash and phosphoric acid 
found in the brown sands. Details are given, supplemented by maps, of the 
distribution of crops over the area studied. Market gardening occupies from 
80 to 95 per cent, of the Greensand derivatives, from 50 to 70 per cent, of 
derivatives of the valley gravel, glacial, and brick earth formations, and only 
4 to 7 per cent, of soils derived from pure Oxford Clay and pure gault. On 
red land (on gault), on pure boulder clay, and on boulder clay overlying Green- 
sand the percentage varies between 16 and 24. Finally the author suggests 
that, in county soil surveys where there are extensive " quaternary " deposits 
giving rise to variations in the soils overlying the geological formations, or where 
numerous geological formations outcrop within a small area, the ordinary soil 
survey should be supplemented by a minute investigation of one or two small 
areas of about 30 square miles. In this way many characteristics of soil and 
crop relationships would be brought out which might otherwise escape notice. 
/. E. W. E. H. 
Mass Mutation in Oenothera pratincola. By H. H. Bartlett (Bot. Gaz. lx. pp. 
425-456 ; 15 figs.) . — " Mass mutation consists in the production of large numbers 
of mutations, in some cases amounting to 100 per cent." ..." It cannct 
be explained by Herebert-Nilsson's Mendelian hypothesis." . . . " As far as 
tested, the characteristic mutations adhere to the following scheme of in- 
heritance : Mutation x Mutation-* Mutation. Mutation x Parent-* Mutation. 
Parent x Mutation-^ Parent. . . . Mass mutation is associated with a high 
degree of sterility, which manifests itself in the production of a greatly reduced 
number of seeds, or in the production of many empty seeds." 
This seems to agree with Darwin's experience in crossing ; i.e. though a cross 
at first stimulates and may increase the fertility, subsequently the self -fertilized 
surpassed those crossed. — G. H. 
Mesembryanthemum transpadense (Bot. Mag. t. 8674A). — South Africa. Nat. 
Ord. Ficoideae, tribe Mesembryeae. Herb, small and stemless. Leaves 8-1 1, 
spreading, if inch long, thick. Flowers nearly sessile, i£ inch across. Petals 
very many, \ inch long, yellow, with a red central line. — G. H. 
Mesembryanthemum tubereulosum (Bot. Mag. t. 8674B).— South Africa. Nat. 
Ord. Ficoideae, tribe Mesembryeae. Herb, small and stemless. Leaves 6-8, 1 
inch long, thick. Flowers sessile, ih inch across. Petals very many, yellow. 
G. H. 
Mosaic Disease of Tobacco. By H. A. Allard (Jour. Agr. Res. v. p. 251, 
Nov. 1915 ; pi.).— The author shows that the virus of the mosaic disease is dis- 
tributed in the tissues of the ovary and ovules, and in the anthers as well as, 
as the author has already shown, in the roots, apparently healthy lower leaves, and 
corollas of the plant* Various malformations may occur as a result of the presence 
of the virus in these tissues, but the disease is not known to be transmitted into 
the embryos of the seeds directly from the mother plant. It is not clear, however, 
to what the effective barrier which appears to be present preventing this infection 
is due. — F. J. C. 
Mulberry, Die-back Disease of. By E. S. Salmon and H. Wormold (Gard. 
Chron. Aug. 26, 1916, p. 95 ; with 3 figs.). — Fusarium lateritium, hitherto regarded 
as a harmless saprophyte in this country, has lately damaged mulberry trees in 
Sussex and Kent, It causes serious havoc in Italy. Pure cultures prove the 
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