462 BOTANICAL GAZETTE [december 



{ 



by Haberlandt, he reports uniformly positive results, both with and without 

 the darkening of the petiole; whence he concludes that "the lens-function does 

 not stand in direct causal connection with the^ perception of the direction of 

 light by the leaf-blade."— C. R. B. 



Branching in palms. — In 1892 Morris^^ brought together what had been 

 recorded concerning the branching of palms, which was regarded as an abnormal 

 phenomenon. Ridley, ^^ who has had eighteen years of experience in the orien- 

 tal tropics, has now much extended our knowledge of this phenomenon. He 

 believes that the greater number of palms are branched at least at base, and 

 that the production of a single axis from a seed may be regarded as the "abnor- 

 mal" condition. Lateral buds are produced at or near the base, and these 

 become erect stems, in some cases the whole plant eventually becoming a bush; 

 or these lateral buds may develop as subterranean branches that send up a suc- 



cession of erect stems (branches). 



palms has been 



thought of only in connection with the crown, but Ridley's observations indi- 



J 



perhaps 



ACK1L\N 



In Agave and Furcraea tem- 



13 Morris, Daniel, On the phenomena concerned in the production of forked 

 and branched palms. Jour. Linn. Soc. London Bot, 29:281. 1892. 



14 Ridley, H. N., Branching in palms. Annals of Botany 21:415-422. pis, 

 34-39- 1907- 



15 FiUTSCH, F. E., and Rich, Florence, Studies on the occurrence and repro- 

 duction of British freshwater algae in nature. I. Preliminary observations on Spiro- 

 gyra. Annals of Botany 21:423-436. 1907. 



1*5 Smith, A. M., On the application of the theory of limiting factors to measure- 

 ments and observation of growth in Ceylon. Annals Roy. Bot. Gardens Peradeniya 

 3:303-375- Pl^' 22-25. 1907- 



t 

 I 



Spirogyra. — Dr. Fritsch and Miss Riches have begun a series of studies of 

 the British freshwater algae, the first one dealing with Spirog}Ta. The principal 

 topics are: '*The occurrence of Spirogyra in nature," *^The reproduction of j 



SpirogjTa in nature," and ** Points of systematic interest." The species examined 

 were either purely vernal or exhibited both a vernal and an autiunnal phase. 

 The autumnal appearance of certain species is thought to be due to certain 

 external conditions that cause a small number of zygospores to germinate. 

 "Reproduction takes place ordinarily in the vernal phase, and is most probably 

 the result of certain periodically recurring combinations of factors, which vary 

 for different species;" in support of which view the authors present a consider- 

 able number of data.— J. M. C. 



Limiting factors and growth.— A. M. SinxH, late a pupil of Blackman at 

 Cambridge, has carried out a thorough study of the rate of growth in a number 

 of plants at different stations in Ceylon, applying to the discussion of his results'^ 



