NOTES AND ABSTRACTS. 
231 
Organic Matter in the Soil, The Influence ol Soil Conditions on the Decom- 
position of. By E. J. Russell and A. Appleyard (Jour. Agr. Sci. viii. June 1917)- 
Decomposition is brought about by bacteria and other micro-organisms. 
Previous observers have not been able to establish any particular connexion 
between the fertility of experimental plots and the number of bacteria found 
in their soils. But since fertility is determined by a number of factors the authors 
have endeavoured to determine what the essential factors are and have continued 
their observations over three seasons. The decompositions observed have been 
the amount of nitrate formation in the soil and the fluctuations of CO s in the 
soil air. When these two sets of observations, together with the bacterial numbers, 
are plotted for a twelve-months period the curves show that they are related : 
a rise in bacterial numbers is accompanied by a rise in CO s and, somewhat later, 
a rise in nitrate. Simultaneous observations of moisture and temperature were 
made, and it became apparent that temperature is a dominating factor. The 
reactions are at a standstill from November to March, but as soon as the tempera- 
ture rises above 5 0 C. bacterial numbers and nitrate and C0 2 contents all increase. 
The activity soon begins to fall off, however, in spite of a favourable temperature, 
and the result is found to be due to another factor, viz. rainfall supplying moisture 
and dissolved oxygen. The curves for these three factors fit the curves for 
bacterial nitrate and C0 2 contents fairly well over most of the year, except for 
a period of depression after the spring rise and a period of autumn activity after 
the summer sluggishness. Comparison of curves for cropped and for fallow 
land show that a growing crop is a fourth and detrimental factor. — /. E. W.E.H. 
Oxidase and Catalase in Plant Tissue, The Relation between. By G. B. 
Reed (Bot. Gaz. Nov. 1916, pp. 409 ; with 1 fig.). — The author describes 
experiments which he performed with pineapple juice, which lead him to con- 
clude that catalase is not universally present in living cells. — R. J. L. 
Oyster Shell Scale, and Scurfy Scale, The. By A. L. Quaintance (U.S.A. 
Dep. Agr., Bur. Entom., Farm. Bull. 723; April 1916; 3 figs.). — The author mentions 
that minute parasitic wasps are often efficient enemies of the oyster shell scale, 
and in some localities apparently hold the insect in check. If these wasps are 
present, small round holes can be seen on the dorsal part of the scale, showing 
where the adult escaped. — V. G. J. 
Pavement Ant, The. By L. B. Smith (U.S.A. Dep. Agr., Virginia 
Truck Exp. Sin., Bull. 16 ; July 1915 ; 6 figs.). — The pavement ant (Tetramorium 
cespitum L.) is a pest of cold-frame and greenhouse crops. In its European 
home the species is known as the common " meadow ant." Since its intro- 
duction to the States it has adapted itself to city conditions, making its nest 
beneath pavements, stone -flagging, brick walls, and cobble-stones, becoming often 
a serious house nuisance, and recently it has been reported as causing injury 
to certain house and greenhouse plants. 
Fumigation with carbon bisulphide has proved the best means of control. 
V. G. J. 
Peach Scab and its Control. By G. W. Keitt (U.S. A . Dep. Agr., Bur. PI. Ind. 
Bull. 395, Jan. 1917, pp. 1-66; 6 plates). — This disease causes serious spotting 
and cracking of the fruit, and spotting of the leaves and twigs. The causal 
organism is Cladosporium carpophilum Thiim., and it is widely distributed 
throughout thirty-four States east of the Rocky Mountains, as well as in Europe 
and South Africa. The author ranks this disease as next in economic importance 
to brown -rot disease. 
The fungus was isolated from peach twigs, fruit, and leaves and grown upon 
thirty media, and it was found that the optimal temperature for growth was be- 
tween 20 0 and 27 0 , and the maximal temperature about 32 0 C. Spores readily 
germinated in sterile distilled water, rain water, and in various nutrient media. 
Peach trees were repeatedly inoculated from the cultures and produced typical 
infections. The period of inoculation of the fungus upon the fruit varied from 
forty-two to seventy-seven days, while upon the twigs and leaves it varied 
from twenty-five to forty-five days. 
The disease is most prevalent in temperate sections where the spring and 
early summer is moist and the growing season is long. The mid-season varieties 
and late varieties are most severely affected by the fungus. 
The control measures include spraying with self -boiled lime sulphur, or finely 
divided sulphur, which have provedsuccessful even in severely attacked orchards. 
A. B. 
