224 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
tendency to alternate fruiting. The figures are percentages of the crops given by 
the former in 1900 and by the latter in 1911. 
1897. 1898. 1899. 1900. 1901. 1902. 1903. 1904. 1905. 
Stirling Castle .3 30 6 100 47 144 o 148 o 
Bramley . . — — — — — — — 35 6 
1906. 1907. 1908. 1909. 1910. 1911. 1912. 1913. 1914. 1915. 
Stirling Castle 144 38 95 171 264 78 47 207 o 549 
Bramley 7 20 7 103 9 100 o 103 o 159 
/. E. W. E. H. 
Fumigant, Para-Dichlorobenzene as an Insecticide. By A. E. Duckett (U.S.A. 
Dep. Agr., Bur. Ent., Bull. 167, December 1915). — Para-dichlorobenzene is a 
colourless crystalline substance (5 1025 times as heavy as air), which volatilizes 
readily in normal circumstances. 
It is harmless to human beings and domestic animals under ordinary con- 
ditions, but is a good specific poison for many insects. 
Para-dichlorobenzene proved especially efficacious against : — 
1. Stored product insects. 2. Case-bearing clothes moths. 3. Cockroaches 
and ants. 4. Museum pests. 5. Miscellaneous house insects, including flies, 
carpet beetles, book lice, mosquitos, etc. etc. — C. P. C. 
Fusarium Blight of the Soybean. By R. O. Cromwell (Jour. Agr. Res. 
viii. March 191 7, pp. 421-439 ; 1 plate, 1 fig.). — The causal organism is found 
to be Fusarium tracheiphilum Smith., and the disease is characterized by a 
chlorosis and shedding of leaves, and ultimately the death of the plant ensues. 
Cultural and morphological studies show that the organism producing the 
disease on the soybean is identical with the organism producing the wilt of 
cowpeas, and inoculation experiments show that, cross inoculations can be 
made. Infection probably occurs through the roots, and a coarse sandy soil 
appears to favour the development of the fungus. 
A fairly complete bibliography is given. — A. B. 
" r |Gas, Illuminating, The Response of Plants to. By Sarah L, Doubt (Boi. 
Gaz. vol. lxiii. No. 3, March 191 7, pp. 209; 6 figs.). — Among the responses 
shown by various plants to illuminating gas were : 
(1) Leaf fall. One part of illuminating gas per 1000 of air caused leaf fall 
in Salvia splendens, Mimosa pudica, &c. 
(2) Epinastic growth of petioles. Traces of gas (50 per 1,000,000 of air) pro- 
duced this effect in a number of plants investigated. [It is impossible to detect 
less than 1 part of gas to 400 of air by the sense of smell.] 
(3) Proliferation tissue in cortex of the stem below the ground was shown 
by the apple, pear, ash, and elm as the result of gas escaping into the soil. (Certain 
bedding plants were found to be injured by the same cause : others were killed 
outright : others dropped their leaves or exhibited epinastic growth of petioles.) 
(5) Root tubercles were produced by traces of gas upon the roots of certain 
plants, e.g. the apple and pear. 
The authoress makes the following practical suggestions for florists ! 
To detect illuminating gas in a greenhouse, some vigorous plants of one of the 
following should be utilized : tomato, castor bean, scarlet sage, or sensitive 
plant. They should have from six to twelve or more leaves. These should be 
placed at various locations throughout the greenhouse and left from twenty- 
four to forty-eight hours with poor ventilation. All will respond to traces of 
illuminating gas within this period at ordinary temperatures. 
With only a trace of gas present in the air the epinastic response will be 
noticeable, andthe bending down of theleaves will increase with the concentration 
of gas present. All these plants will drop their leaves with a concentration 
below the limit of the odour of gas. The older leaves fall first, the younger 
leaves being retained until there is one part of illuminating gas to 1000 of 
air.— R. J. L. 
Gerbera Jamesoni fl. pi. By C. Albert (Le Jard. vol, xxxi. p. 156). — A 
double variety of Gerbera Jamesoni, raised on the Riviera, is of great ornamental 
value. The flowers are six inches in diameter with three rows of petals. The 
flowers exhibit a great variety of colour — pink, salmon fawn, amber, &c. The 
plants thrive on a rich, well -drained soil. — S. E. W. 
Gladiolus, Hard Rot Disease of. By L. M. Massey (U.S.A. Exp. Stn., 
Cornell, Bull, 380, Sept. 1916, pp. 150-181 ; 7 figs;, 2 plates). — The disease 
