1918] 



AGRICULTUEAL BOTANY. 225 



P. rhainni), P. taraxacl, P. sorglii, P. phlci-prafcnsis, P. pohjgoni, Uromycea 

 trifolii, Coleosporium solidaginis, Melaw psora Mglowii, M. medusa;, Cronartium 

 cumptoiiia; (^cidial stage, Peridcnnium comptoniw), and C. comandrw. 



The general factors'controlling spore germination appear to be temperature 

 and moisture. Other factors are discussed in connection with the work of 

 other investigators. 



Light and pycnidia formation in the Sphseropsidales, E. Levin {Rpt. Mich. 

 Acad. Sci., n {1915}, pp. 134- 135).— In experiments for testing the effect of 

 light in connection with the germination of seven members of the Sphseropsi- 

 dales, only three germinated at all in the darkness, the percentage being about 

 30 to 40, while in the light representatives of all of the genera germinated, 

 giving percentages ranging from 30 to 100. The cultures obtained in the dark- 

 ness resembled in all respects those obtained in the light. 



Some cultural characteristics of Pestalozzia funera, P. V. Siggers (Rpt. 

 Mich. Acad. ScL, It {1915} , p. 1J,1, pi. i).— Brief accounts are given of the re- 

 sults as regards the vegetative growth obtained in 14 days with P. lunera 

 grown on gelatin and upon several kinds of agar. 



The colorimetric determination of hydrogen ion concentration and its ap- 

 plications in bacteriology, W. M. Claek and H. A. Lubs {Jour. Bact., 2 {1911), 

 Nos. 1, pp. l-SJf, figs. 4; 2, pp. 109-136, pi. 1, figs. 2; S, pp. 191-236, fig. 1).— 

 The authors have made a study of the colorimetric method of determining 

 hydrogen ion concentration, testing a number of indicators in a wide variety 

 of solutions, such as are used for the cultivation of bacteria, and have carried 

 out other related studies as described. They conclude that, with the improve- 

 ments presented, the colorimetric method is available for routine as well aa 

 for research work in bacteriology. 



A new apparatus for aseptic ultrafiltration, R. B. Smith {Phytopathology, 

 7 {1917), No. 4, pp. 290-293, figs. 2).— xV description is given of an apparatus 

 designed for the production of aseptically filtered juice from unheated plant 

 extract that may be used as a culture meilium. 



Irritability of the pollen-presentation mechanism in the Compositje, J. 

 Small {Ann. Hot. [London^, 31 {1917), No. 122, pp. 261-268).— A record is 

 made of the types and degrees of irritability observed in the pollen-presentation 

 mechanism of 140 species and varieties of Compositje. Of these, 64 per cent 

 exhibit this phenomenon, and it was observed in all tribes of this family except 

 the Eui)atorieai and the Vernoniea;. Notes are given also on certain special 

 cases observed, as, for example, the explosive irritability in the Mutisiese and 

 a peculiar slow movement in the Cichorieifi. 



Endothia pigments, I, L. A. Hawkins and N. E. Stevens {Amer. Jour. Bot., 

 4 {1917), No. 6, pp. 3.36-353, figs. 6).— From the experimental work here de- 

 scribed it appears that there are at least three different pigments formed by 

 species of Endothia, pigment A, apparently common to all the species; pig- 

 ment B, present in E. fluens and probably in all species showing a similar 

 spectral transmission of the acid alcohol solutions; and pigment C, present 

 in the two groups typified by E. fluens and E. parasitica. These pigments may 

 be closely related chemically, perhaps derivatives of the same substance, as 

 they are similar in many particulars. The data and opinions of other investi- 

 gators are considered in connection with detailed observations by the authors. 

 Observations on an Achlya lacking sexual reproduction, W. H. Weston 

 {Amer. Jour. Bot., 4 UOn), No. 6. pp. 354-367, pi. i).-The fungus here de- 

 scribed, though presenting characters distinctive of the genus Achlya as regards 

 zoospore production, liberation, character, and behavior, is distinguished from 

 most species of this genus by its lack of sexual reproduction and by its non- 

 production of oogonia and antheridia under the culture methods usually sue- 



