NOTES AND ABSTRACTS. 
229 
Nicotine as an Insecticide. — By N. E. Mclndoo (Jour. Agr. Res. vii. pp. 89- 
122, Oct. 1916 ; plates). — Experiments carried out by the author failed to 
demonstrate the entrance of nicotine into the body of insects either through the 
spiracles or the integuments. The fumes or odoriferous particles, however, 
of sprays, fumigsnts, and tobacco powder pass into the tracheae and are 
widely distributed over the insects' tissues. The nicotine kills the insect by 
paralysis, the trouble travelling along the ventral nerve cord from the abdomen 
to the brain. Exactly how the paralysis is brought about is not evident, but the 
author suggests that it may be by means of interference with oxygen supplies. 
F. J. C. 
Nicotine Sulphate and Fish-oil Soap Sprays. By L. B. Smith {Jour. Agr. 
Res. vii. pp. 389-399). — A loss of both wetting power and efficiency occurred 
with higher concentrations of the two sprays mentioned when used on peas, 
spinach, and strawberries against aphis and red-spider attacks. When more 
than 4 lb. soap were used with 10 oz. nicotine sulphate to 50 gallons water, or 
more than 8| oz. nicotine sulphate to 5 lb. fish-oil soap to 50 gallons of water, 
both wetting power and efficiency were reduced. — F. J. C. 
Nitrogen Fixation and Nitrification, Some Factors Influencing. By B. 
Williams (Bot. Gaz. vol. lxii. Oct. 1916). — In a recent article by Lipman 
and Sharp it has been suggested that there are really two maxima of fixation 
with reference to moisture content, the one that is most favourable to aerobic 
bacteria, and the other at which anaerobic forms flourish best. 
The first set of experiments conducted by the author showed that one at 
least of the free nitrogen -fixing organisms materially deteriorated through the 
process of drying attendant upon ten months' storage of the soil in the laboratory. 
To determine to what extent drying affected the fixing power of the soils 
as a whole was the object of the next series of tests. It was found that the soils 
lost 24 to 43 per cent, of their original efficiency for fixing nitrogen during a 
period of fifteen months' storage. 
In tests conducted with a rich garden soil known to have a vigorous Azotobacter 
flora, the nitrogen -fixing flora was found to decrease considerably under the 
influence of drying. After fifteen months, however, a number of soils retained 
considerable ability to fix nitrogen, which indicates that some species at least 
offer great resistance to drying. Azotobacter was shown to be more easily 
attenuated than some other species. 
The nitrogen -fixing flora is so intimately connected with the humus content 
of a soil that this is undoubtedly the most important influence in connexion with 
the process. It is extremely doubtful whether a toxic condition of the soil exerts 
inimical effects upon soil bacteria. 
In experiments conducted with lime it was found that where there is some 
development of the nitrifying flora in the soil originally, the effects of lime are 
decidedly more evident than in those soils apparently devoid of nitrifying power. 
R. J. L. 
Nitrogen in Fseces, The Fixation of. By E. H. Richards (Jour. Agr. Set. 
yiii. June 1917)- — Both horse and bullock manure when fermented in bulk 
in presence of air and sufficient moisture and calcium carbonate will fix nitrogen. 
The fixation is brought about by Azotobacter and Bacillus lactis aerogenes work- 
ing together. Fixation does not occur in manure from bullocks fed on grass : 
cake-feeding is essential in their case. The fixation is also reduced greatly in 
the case of horses fed on grass alone, the greatest fixation occurring when the 
horses are fed on corn and hay. This is due to the necessity for the presence of 
carbohydrates for the bacteria to feed on ; more of them pass through the 
stomach of the horse undigested than through the bullock. The quantity of 
nitrogen added to horse manure as a result of nitrogen fixation may in the 
most favourable circumstances amount to as much as 50 per cent, of the original 
nitrogen and be complete in about a month. Nitrogen fixation would also 
occur in soil manured with horse dung, but the addition of nitrogen in these 
circumstances would be very small. — /. E. W. E. H. 
Oenothera Lamarckiana mut. velutina. By Hugo De Vries (Bot. Gas. vol. Ixiii, 
No. 1, Jan. 191 7, pp. 1-24; with a coloured plate depicting O. Lamarckiana 
mut. velutina (O. blandina) and O. blandina mut. spiralis). —The following is 
the substance of the author's summary of his investigations : — 
O. Lamarckiana mut. velutina (0. blandina) arose from the family of O. La- 
marckiana mut. lata x semilata among seeds of the third generation in three 
specimens. Of one of these a second generation was cultivated, and of one of 
the others four successive generations : making in all over 3,000 plants. All 
