838 SUMMARY OF CURRENT RESEARCHES RELATING TO 



physiological effect was exerted by the red. By placing the prism 

 in the greenish-yellow part of the spectrum, a greenish-yellow and a 

 violet image were obtained. The latter contained all the rays ab- 

 sorbed by chlorophyll, whilst the former contained only the green 

 which is reflected by vegetation. In this case the maximum effects 

 were exerted by the violet. 



It follows from these results that chlorophyll acts as a true 

 sensitizer, undergoing decomposition itself, and promoting the de- 

 composition of carbonic anhydride in those parts of the spectrum 

 which it absorbs. The different rays absorbed by chlorophyll produce 

 decomposition in very different degrees, the maximum decomposition 

 coinciding in a remarkable manner with the maximum energy in the 

 normal spectrum as measured by Langley and Abney. It would 

 seem, therefore, that it is the amplitude rather than the period of the 

 vibrations which brings about that disturbance of the carbonic 

 anhydride molecule which finally results in its dissociation. The 

 chemical action of light on the photographic plate seems to be 

 strictly analogous to its physiological action on the living plant, 

 provided that, as in the case of chlorophyll, the absorption phenomena 

 are identical in both cases. 



B. CRYPTOGAMIA. 



Cell-wall-thickenings and Cellulin-grains in Chara and Vau- 

 cheria.* — Prof, G. Schaarschmidt has observed these structures in 

 Chara hisjoida and Vaucheria sesstUs. They are especially abundant 

 on plants grown in a room. They are of various forms, cylindrical, 

 conical, or ribbon-shaped, occasionally branched or united in groups, 

 or of larger size and undulating, or very rarely empty and vesicular. 

 They make their first appearance as small elevations on the inside of 

 the cell-wall, often very closely packed ; developing then into a 

 cylindrical-conical form, manifesting a distinct lamination, and with 

 either a " nucleus " or crevice near the base. The undulating thick- 

 enings are found especially in the antheridia and oogonia, on septa 

 formed as the result of injury. The protoplasm collects in large 

 quantities at the spots where these thickenings are taking place ; it 

 contains but a small number of chlorophyll-grains, and finally dis- 

 appears with the exception of a very thin layer, which shows very 

 beautifully the hyaloplasmatic membrane of the chlorophyll-grains. 

 In Vaucheria and many other fresh- water algse the cell- wall is im- 

 pregnated with various incrusting substances of unknown composition. 



These thickenings are regarded by the author as pathological 

 products, and are often accompanied by abnormal structures such as, 

 in Vaucheria, the septation of the filaments. The portions of proto- 

 plasm separated by transverse thickenings develope into gemmae, or 

 into a multicellular or branched septated form, the " conferva " and 

 " cladophora " condition respectively. These forms are in no way 

 connected with the Gongrosira-condition. 



* Magy. Noven. Lapok., viii. pp. 1-13 (1 pi.). See Bot. Centralbl., xxii. 

 (1885) p. 1. 



