1907] CURRENT LITERATURE 287 
from 3-6 times in Jena glass or in platinum dishes; the water was redistilled and 
kept in Jena or in Thiiringen glass. The most important of BENECKE’s results, 
and those in which he is at variance with the investigators mentioned above, are 
as follows: (1) Dextrose or ammonium salts cannot be substituted for asparagin 
in 48 simple solution, asparagin 0.25 per cent., magnesium sulfate 0.05 per 
-, potassium phosphate 0.02 per cent. (2) Potash is necessary for develop- 
ment, although a very small amount of K-ions suffices for growth and pigment 
production. (3) Potassium cannot be replaced by lithium, sodium, or ammo- 
can be replaced by rubidium and caesium, though not to the same 
degree, the presence of 0.0000015 per cent. of KCI being sufficient for develop- 
ment, while RbCl must be 10 times, and CsCl 100 times, as strong. The latter 
are also more toxic than KCl in concentrated solutions. (4) The presence of 
magnesium in the solution is necessary for development. Growth occurred in 
Mg-free solutions in Jena glass, which has 5 per cent. Mg in it, while no growth 
was obtained in Vienna glass. This Mg relation has been a stumbling-block for 
many investigators. On the other hand, the conclusion of most of the other 
authors that phosphate is essential in the solution is confirmed by BENECKE, as 
is also the observation of JoRDAN and of NorssKE that the acid group SO, is 
necessary for pigment development in B. fluorescens and B. pyocyaneus. BE- 
NECKE, however, does not distinguish between the two pigments produced by the 
latter organism, which may not be alike dependent upon sulfate —Mary HEr- 
FERAN. 
Infectious chlorosis.— Further studies of BAur® on the infectious chlorosis 
of the Malvaceae have shown that green shoots which occasionally appear on 
variegated plants of Abutilon Thompsoni, Hort., are entirely immune to the disease 
and remain so. If a scion from one of these immune shoots is grafted upon a 
variegated plant, the scion produces only green leaves. If another scion of a 
green susceptible variety is grafted upon the first, the second scion will become 
variegated, showing that the virus is conducted unchanged through the immune 
piece. If, however, the experiment is conducted by using the immune species 
Lavatera arborea L. as the intermediate piece, no infection occurs in the second 
scion. In the first instance the intermediate plant is immune but does not affect 
the virus; in the second instance the virus is evidently destroyed. In his former 
paper BAUER showed that the virus causing chlorosis was developed only in the 
light. In the present paper the light relation is more fully investigated. It is 
found that somewhat shaded individuals, as when growing under shrubbery, 
lose their variegation, although growth is not greatly influenced. The optimum 
for virus formation, therefore, lies much above that for growth. Although shading 
the plants resulted in a diminution of the white areas, it was not possible by 
increased illumination to increase the areas above a certain maximum w 
6 Baur, ERWIN, Weitere Mitteilungen iiber die infectiése Chlorose der Mal- 
vaceen und iiber einige analoge Erscheinungen bei Ligustrum und Laburnum. Ber. 
Deutsch. Bot. Gesells. 24:416-428. 
