538 BOTANICAL GAZETTE [DECEMBER 
the natural vegetation.” There are _ of plants of fodder value, valuable 
woods medicinal plants. Four appendices 
also deal with Cyperaceae, pHs nicoeot Eucalyptus), Eucalyptus, and 
Acacia. Four new genera are established by Ewart as follows: Spathia and 
Setosa (Gramineae), Rossittia (Rutaceae), and Carpentea (Convolvulaceae); 
and in addition 30 new species are described.—J. M. C 
NOTES FOR STUDENTS 
Phenomena of parasitism.—In a summary of his researches on the processes 
involved in the attacks of plant tissues by Botrytis cinerea, BRowN’ gives a 
review of the work already published and a forecast of investigations now in 
progress. The published work has already been noted in this journal,s and 
we need only allude to the author’s speculation on the question whether 
the effects produced by the fungous extract on the cell wall and on the proto- 
plasm are attributable to the same or to different substances. In the absence of 
any means of disentangling the mixture of substances occurring in plant ex- 
tracts or of excluding the action of all but one, it seems futile to speculate on 
the specificity of action of any of the substances. Future work as outlined by 
the author is to cover such problems as the germinating capacity of spores in 
water and in nutrient solutions, the diffusion of substances from age cells into 
water placed on the cuticle, and the physics of cuticular resistance 
The fourth contribution to this series’ deals with some £ the factors 
influencing the production of cytase in cultures of Botrytis cinerea. In the 
first paper of the series it was shown that very active cytolytic extracts could 
be obtained from young germ tubes of the spores of the fungus. As might be 
expected, therefore, the activity of the enzyme extracted from cultures of differ- 
ent ages is proportional to the quantity of actively growing mycelium. Con- 
sequently, with respect to enzymatic activity, a growing culture soon reaches 
a maximum, and thereafter the enzyme content rapidly diminishes. The 
enzyme content of the culture fluid follows a course in general parallel to that 
of the mycelium. Dilution of the enzyme extract by a similar extract deacti- 
vated by exposure to a temperature of 65° has the same effect as dilution by 
caused by the development of inhibiting substances. As might appear self- 
evident, cultures thickly sown with spores gave stronger enzyme extracts than 
cultures thinly sown. The experiments confirm the former conclusions that 
Acast * ton ka tc. ol ing ds of the hyphae.—H. HASSEL- 
BRING. 
3 Brown, W., On the physiology of parasitism. New a hy tal. 16:109-126, 1917. 
4 Rev. Bor. Gaz. 61:80. 1916; 63:240. 1917. 
5’ Brown, W., Studies in the physiology of parasitism. -IV. On the distribution 
of cytase in cultures of Botrytis cinerea. Ann, Botany 31: ao-uek: 1917. : 
