Physiologie. — Algae. 297 



The amount of growth, or increase in volurne, that may 

 be accomplished by the shoot by the extension of the imper- 

 fectly developed tissues in the absence oi illumination is subject 

 to great Variation. In many cases the total length, diameter 

 and volume of the etiolated shoot may be actually less than 

 the normal one, while in other cases it is more. Nor is 

 evidence afforded by the behaviour of plants in darkness to 

 Warrant the conclusion that light directly affects the rate of 

 growth. Light does not exert a direct retarding, or paratonic 

 influence on the processes of growth, but the slowing down of 

 the rate of growth under the influence oi light is an irritable 

 response. 



Attention may be called to the index in wich citations of 

 the work of previous investigators are made, in addition to the 

 foot note references in the text. H. M. Richards (New York). 



Neubert, R., Untersuchungen über die Nutations- 

 krümmungen des Keimblattes von Allium. (Jahrb. 

 f. wissenschaftliche Botanik. XXXVIII. 1902. Heft 1. p. 119 

 — 145. Mit 10 Figuren im Text.) 



Verf. hat sich die Aufgabe gestellt, näher zu untersuchen, 

 wie das Knie des die Erde durchbrechenden Keimblattes und 

 seine nachträgliche Streckung zu Stande kommt. Er findet, 

 dass die Nutationskrümmung ihrer Anlage nach autonom ist, 

 jedoch durch negativen Geotropismus und Substratbeschaffen- 

 heit in der weiteren Ausgestaltung beeinflusst wird. Ihre Aus- 

 gleichung erfolgt vornehmlich autonom, aber auch hier kommt 

 der Schwerkraft ein orientirender Einfluss zu. Die bei Allium 

 am Knie des Keimblattes auftretende Portuberanz zeigte sich in 

 ihrer Ausbildung abhängig von der Tiefenlage des Samens, 

 speciell von Dunkelheit und Reibung. Noll. 



Fritsch, F. E., Algoiogical Notes. IV. Remarksonthe 

 periodical development of the algae in the arti- 

 ficial waters at Kew. (Annais of Botany. Vol. XVII. 

 January 1903. No. LXV. p. 274—278.) 



The author published tables illustrating the development 

 throughout the year of algae in a Tank and in the Lake in 

 the Royal Gardens, Kew. He considers that the difference in 

 the monthly character of the flora of the Tank is increased by 

 the forthightly removal of large masses of algae during the 

 summer ; but even in the Lake, where no such removal takes 

 place, the periodicity of the flora is well marked. The maximum 

 development takes place in August and September, when 

 Enteromorpha intestinalis, Tetraspora gelatinosa and Oscillaria 

 nigra are all very abundant. Remarks are also made on the 

 algae which occur in the tanks of the hot-houses. 



E. S. Gepp (nee Barton). 



