480 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
control lay in the use of chemical sprays. Comparative tests were made with 
sodium arsenate, ferrous sulphate, carbon bisulphide, &c. Of these, sodium 
arsenate is the most effective and is recommended for use. This substance 
has been used for five years for weed eradication in Hawaii with most successful 
results. 
In view of the possible injury to crops from the continued use of this spray, 
a series of experiments were undertaken to determine its fate and influence 
upon plant growth and upon nitrification and ammonification of the soil. It 
was shown that soils possess strong fixing power for arsenic, and where the sodium 
arsenate spray is used for destroying weeds the arsenic will be deposited in the 
surface soil -and will remain in spite of the leaching action of rains or irrigation. 
The chemical reactions involved are a replacement of the solution of iron, calcium, 
magnesium, and humus, owing in part to a hydrolysis of the sodium arsenate 
in solution ; also a combination with the dibasic and tribasic elements to form 
the difficultly soluble arsenites and arsenates. — A. B. 
Asparagus Beetle Egg Parasite. By F. A. Johnston {Jour. Agr. Sci. iv. 
p. 363 ; July 191 5 ; pi.). — The insect Tetrastichus asparagi was believed to develop 
in and feed upon the eggs of the asparagus beetle, but observations upon its life- 
history show that it oviposits in the host's egg. and the egg subsequently hatches 
into the beetle larva, which feeds in the normal way and enters the soil in order 
to pupate, but is unable to do so. The parasites have, by this time, totally con- 
sumed the larva and pass from it into the cell it has formed, pupate there, and 
later emerge as adults. The winter is passed in the host cell in the earth, so 
that it would not be difficult to distribute the parasite by transporting some of 
the soil. — F. J. C. 
Asparagus, Ornamental. By E. Plateau (Rev. Hort. May 16, 1916). — Descrip- 
tion of the various types of Asparagus available for decorative purposes.' — C. T. D. 
Bacillus radieicola of Canada Field Pea, Physiological Studies of. By 
Martin Prucha (U.S.A. Agr. Exp. Sin., Cornell, Mem. No. 5, March 1915, 
pp. 3-83). — The objects of this memoir were (1) the isolation and identification 
of the organism causing nodules on the roots of Canada field pea ; (2) a study of 
the influence of various factors on nodule development in this plant when grown 
in water and soil cultures ; (3) a study of the influence of various environmental 
conditions on the infecting power of the organism. 
As a result of the author's experiments, the following conclusions were 
arrived at : — 
The causal organism in the case of the Canada field pea nodules is Bacillus 
radieicola. Its flagella are peritrichic, eight the largest number found, and its 
group number on chart of American bacteriologists is B222. 2322033. 
Nodules developed both in light and in darkness. A larger number, however, 
developed in darkness. 
Nodules developed readily in soil extract and in synthetic nutrient solutions 
in which the nitrates were omitted or replaced by chlorides. The nodules 
continued to increase in number as long as the plants continued to grow. 
In a full nutrient solution containing nitrates a few nodules may develop 
immediately after inoculation, but a subsequent continual development of 
nodules seems to be inhibited. 
The addition of KNO,, Ca(N0 3 ) 2 , NH 4 C1, FeCl 3 , KC1, or peptone to sandy 
soil, in the proportion of 0*25 gram of the salts to 300 grams of the soil air-dry, 
had an inhibiting effect on nodule development, but the addition of MgS0 4 , 
KH 2 P0 4 , Ca(H 2 P0 4 ) 2 and tannic acid had a beneficial effect on nodule develop- 
ment in this plant. The organism multiplies readily in some soils and in various 
substances ; as many as 10 million organisms per gram developed in wheat bran 
and in ground peas. 
The infecting power of B. radieicola was not affected after the organism 
had been kept on medium 335 (i.e. containing nitrogen) for 2-| years in the 
laboratory, the culture being transferred once each month. — A. B. 
Bacteria, Life Cycles of. By F. Lohnis and N. R. Smith (Jour. Agr. Res. 
vol. vi. No. 18, July 1916, pp. 675-702 ; 7 plates, 1 fig.). — A comparative study 
of forty -two strains of bacteria show that the life cycles of these micro-organisms 
are not less complicated than those of other micro-organisms. All the bacteria 
studied live alternately in an organized and in an amorphous stage. The latter 
has been called the " symplastic " stage, because the living matter previously 
enclosed in separate cell walls undergoes a thorough mixing, either by complete 
disintegration of both cell wall and cell contents, or a mixing together of cell 
