574 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
will grow quite well in deep gritty loam. It is easily raised from seed, but by 
no means easy to increase otherwise. Slugs are fond of it. — H. R. D. 
Skin Irritation, Plants and. By J. H. Maiden (Agr. Gaz. N.S.W. vol. xxix. 
PP- 344-345)- — Inflammation of the skin is caused by contact with the following 
plants : Noogoora Burr (Xanthium strumarium), Stinkwort (Inula graveolens), 
and Senecio Hectori. — S. E. W s 
Snowdrops, Autumn Flowering. By E. A. Bowles (Gard. p. 4, Jan. 6, 191 7). — 
The suggestion that these are forms of Galanthus nivalis does not apply to the 
two known as G. Olgae and G. Rachelae which flower in the end of October. 
G. cilicius must be reckoned as a form of G. nivalis, showing its buds before the 
shortest day, and so earlier than the type. G. byzantinus and G. Elwesii are apt 
to flower early the first season after planting, and then gradually accommodate 
themselves to the snowdrop season, but certain individuals of G. byzantinus 
retain the early- flowering habit (in flower December 20). G. Elsae and G. Olgae 
probably prove consistently autumnal. — H. R, D. 
Soil Acidity and the Hydrolytic Ratio in Soils. By C. H. Spurway (Jour. 
Agr. Res. xi. 12, pp. 659-672). — Investigations in soil acidity indicate a relation- 
ship between iron and aluminium compounds in soils and their reaction to litmus 
paper and phenolphthalei ndicator. The author finds that all the acid soils 
have ratios CaO : Fe 2 0 3 + A1 2 0 8 above 1 : 1-3, and all alkali soils have 
ratios below this figure. He believes that the reactions of the soils depend 
chiefly upon the hydrolytic ratios existing between the compounds of the alkali 
earths and iron and aluminium. 
A method of determining the calcium oxide required to neutralize a soil by 
indirect titration is described where a standardized calcium hydroxide solution 
is allowed to react with varying amounts of soils. The concentrations of soil 
and solution giving a neutral reaction are found by comparing the electrical 
resistance of the several solutions, and also by phenolphthalein. The greatest 
electrical resistance and faint colour of the indicator is coincident with the 
concentration giving a neutral reaction. 
The quantities of lime required to neutralize the acid soils is determined by 
computing the quantities of calcium oxide necessary to add to the acid-soluble 
calcium oxide found in the soils to bring the ratios CaO : Fe 2 O s + A1 2 0 to 1 : 1*3. 
The quantity required corresponds closely with the quantities required when 
determined by the indirect titration method . 
A short bibliography is appended. — A. B. 
Soil, Effect of Decomposing Organic Matter on the Solubility of Certain 
Inorganic Constituents of the. By C. A. Jensen (Jour. Agr. Res.ix. pp. 253-268). 
— The author finds the solubility of compounds of calcium, magnesium, iron, 
and phosphoric acid in soils measurably increased by the addition of green 
manures, stable manures, and their extracts. — F. J, C, 
Soil Flora Studies. By H. Joel Conn (U.S.A. Exp. Stn., New York, Tech. 
Bull. 57, 58, 59, 60, Jan. -March 1917). — The first of this series deals with the 
general characteristics of the microscopical flora of the soil, and the methods 
best adapted to the study of the soil flora. The second bulletin deals with the 
spore-forming bacteria in soil; the third with the non-spore-forming bacteria; 
and the last one deals with the form Actinomycetes in soil. 
The soils were obtained from various parts of New York State, and the results 
obtained have extended over eight years. The determinations were made by 
the plate method, since this enabled the relative number of different organisms 
in the soil to be ascertained. Over 1,000 pure cultures of these organisms were 
made, and their characteristics studied by various methods. Non-spore-forming 
bacteria (mostly non-motile rods) were most abundant, and next to these are the 
various types of Actinomycetes. Spore-forming bacteria have also been found, 
but in no great numbers. The author's conclusions may be set forth as follows : 
1. Of the spore-forming bacteria in these soils, Bacillus megatherium 
(Debary), B. mycoides (Fliigge), B. cereus (Frankland), were the most abundant. 
B. simplex (Gottheil) also occurs in somewhat smaller numbers. These bacteria 
are ordinarily inactive in soil and form a relatively small part of the flora of the 
soil, and seem to occur in normal soil only as spores. 
2. The largest number of soil bacteria were found to be non-spore-forming 
organisms. Of these the most abundant type is B. fiuorescens (Fliigge) Migula, 
especially in well-aerated soils, or soils containing organic matter recently added, 
but in older soils the numbers of this organism are considerably reduced. This 
seems to indicate that they are amongst the most active of soil micro-organisms. 
