Researches in Vegetable Physiology. 145 



His results agree in all respects with those of the two natu- 

 ralists above mentioned. 



Lastly, M. Roze* concludes some investigations of the same 

 kind hj saying that these movements of the granules of chlo- 

 rophyl must be accompanied by a displacement of the whole 

 protoplasmic mass. The anatomical relations of the different 

 parts of the cell render this, so to speak, necessary and evident. 

 By taking up similar researches, Dr. B. Frank t has disco- 

 vered an entirely new property of chlorophyl, a property the 

 importance of which cannot be well appreciated except by his 

 subsequent investigations. According to Dr. Frank, the 

 granules of chlorophyl unite to all the other characteristic 

 features of their already complicated organization a marked 

 tendency to move in the interior of the cell to the side which 

 is most iUuminated, exactly as zoospores do when placed in a 

 plate near a window. To ascertain this phenomenon we must 

 of course have recourse to plants with rather large cells, such 

 as are often presented by aquatic plants. The first observa- 

 tions were made on leaves of Sagittaria sagittifolia, a plant of 

 which was grown near a window. The general distribution 

 of the granules of chlorophyl during the day and night at 

 first followed strictly the laws laid down by MM. Famintzin 

 and Borodin ; but as the unilateral illumination was prolonged 

 the aspect of affairs changed, and the granules of chlorophyl 

 showed a more and more marked tendency to accumulate on 

 the most strongly illuminated side of the cell. 



The same facts were reproduced in the cells of the prothal- 

 lium of various ferns and in the leaves of a moss, the Mnium 

 rostratum, Schwsegr. The position, direction, or orientation 

 of the cells has no influence upon the phenomenon, which is 

 equally well manifested in all cases, in diffused light as well 

 as in the sun's rays. With regard to the different regions of 

 the spectrum the author was unable to make any marked di- 

 stinction. In a general way, diminution of the intensity of 

 the light renders the phenomenon less striking and sometimes 

 irregular ; it is, however, always manifested, whatever may 

 be the colour of the luminous rays. 



Dr. Frank thought he could associate this displacement of 

 the grains of chlorophyl with peculiar protoplasmic currents. 

 Perhaps this work will become the origin of interesting obser- 

 vations upon the i-elations of light to the intracellular currents, 

 phenomena which are still very imperfectly known. 



As we are speaking of movements, we may indicate in 



* Coinptes Rendus, 1870, tome Ixx. 

 t Botanische Zeitimg, 1871, No. 14. 



