242 Allgemeines. — Morphologie etc. — Physiologie. 



(chap. VII), adaptation (chap. VIII). Throughout the volume is 

 illustrated with textfigures, which help to illumine the text. 



Harshberger. 



Dopsey, M. T., Variation in the Floral Structure of Vüts. 

 (Bull. Torr. Bot. Club XXXIX. p. 37-52 with 3 pl. 1912.) 



The author disousses the general floral habits of Vttis and the 

 variations in flower types and in the number and structure of the 

 various parts of the flower. He finds that Väis is dioecious, poly- 

 gamodioecious, or perfect. The flower forms, which occur, are the 

 staminata, and the perfect 1) with upright and 2) with reflexed 

 staraens. In Vitts, the flower forms resemble those of the closely 

 related genera, Ctssus. Ampelopsis, and Parthenocissus. The typical 

 grape flower is 5-merous, although about 30 percent show a Varia- 

 tion from this plan. The number of stamens per flower varies from 

 3 to 9 and the dehiscence of the corolla seems to be a result of 

 drying. An increase in the number of stamens is associated with 

 an increase in the number of carpels. The staminate flowers have 

 rudimentary pistils, in which the Stigmas and ovules are abortive. 



Harshberger. 



Atkins, W. R. G., Oxvdases and their Inhibitors in Plant 

 Tissues. (Sei. Proc. Roy. Dublin Soc. XIV. p. 144-156. 1913.) 



In earlier work on osmotic pressures in plants, the brown 

 colour of the sap expressed from many tissues was noticed, an 

 efi"ect due to the action of oxydases, but in some cases the sap was 

 light in colour and no oxydases could be detected. Other investi- 

 gators have shown that tannin and sugars hinder the action of 

 oxydase on the usual reagents employed for the detection of the 

 enzyme, but though in some cases tannin was found by the writer 

 in undarkened sap, some cases remained which are now investi- 

 gated. The writer finds that while plants yielding a brown sap 

 always give the direct oxydase reaction, those yielding light-coloured 

 sap either give the indirect reaction or contain tannin or some 

 reducing agent. In Iris germanica the presence of a strong reducing 

 agent prevents the detection of oxydase in certain tissues, but this 

 agent may be removed by prolonged dialysis and the presence of 

 oxydase may then be demonstrated. Other cases are cited, affor- 

 ding fresh evidence for the view that oxydases are universally 

 present in plant tissues. The colours of the perianth leaves of six 

 varieties of Iris are shown to be due to the presence or absence 

 of a yellow plastid pigment and an anthocyan pigment which is 

 formed by the action of the epidermal Peroxydase on a chromogen; 

 this production of pigment may be inhibited by the presence of 

 the reducing substance of Iris leaf-sap. F. Cavers. 



Briggs, L. J. and H. L. Shantz. The Water Requirement 

 of Plants. Part I. In ves tigations in the Great Plains 

 in 1910 and 1911, Part II. A Review ot the Literature. 

 (Bull. 284 and 285 U. S. Bureau of Plant Industry. 1913.) 



The term "water requirement" is used in this paper to indicate the 

 ratio of the weight of water absorbed by a plant during its growth of 

 the weight of the drymatler produced. The investigation had for its 



