314 SUMMARY OF CURRENT RESEARCHES RELATING TO 



BOTANY. 



GENERAL, 

 Including the Anatomy and Physiology of Seed Plants. 



Cytology, 

 including Cell-Contents. 



Protoplasmic Continuity in Cryptogams.* — Kienitz-Gerloff has 

 examined a number of the lower plants in relation to this question. 

 The method followed was that of Arthur Meyer. Amongst Liverworts 

 connecting-threads were sought for in vain in Fegatella, Marchantia, 

 Biccia, and Anthoceros, but Beboulia, Metzgeria, Lepidozia, and Junger- 

 mannia bicuspidata were found to be suitable objects. In the leaf of 

 the last-named form the threads (Plasmodesmen) were particularly 

 striking. In Lepidozia the continuity was observed in the tissue of the 

 sporophyte (seta). Among mosses the threads were found in a number 

 of genera, but in Pohjtrichim formosum they were very striking in the 

 stem and seta, and are described as the finest yet observed in plants. 

 The author considers that in the filamentous algaa the cells are probably 

 quite separate from one another ; but though protoplasmic continuity 

 probably exists in the rest of the algfe, he was unable to observe it in 

 Fueus, in which it has been described by Kohl. In the case of the 

 FlorideaB he was unable to determine that in Batracliospermum and 

 Polysiphonia connecting-threads existed in the well-marked pit-closing 

 membranes. Various cases in which the Plasmodesmen have been 

 observed in Fungi and Lichens are quoted, and the author has also made 

 observation himself; the most striking connection in the latter group 

 was observed in the hypothecium of Peltigera carina and P. polydadyla. 



The question is discussed as to the part the protoplasmic threads 

 play in the conduction of stimuli and the translocation of food-material 

 from cell to cell, and also as to the passage of the protoplasmic contents 

 from one cell to another, which has been described in the fungi. 



Protoplasmic Streaming in Plants.f — A. J. Ewart gives an abstract 

 of results of observation on this phenomenon. The energy of movement 

 is generated in the moving layers, which are retarded by friction against 

 the non-moving ectoplasm, and to a much less extent by friction against 

 the cell-sap which is passively carried with the stream. The velocity 

 depends largely on the viscosity of the protoplasm. Gravity exercises 

 little or no influence upon streaming in small cells, and only a very 

 slight action in the case of large ones. As temperature rises the viscosity 

 of the plasma decreases. The author discusses the physics of the move- 

 ment, and also its relation to external stimuli, such as temperature, li^ht,. 

 and mechanical, chemical, and electrical stimuli. 



* Ber. Deutsch. Bot. Ges., xx. (1902) pp. 93-117 (1 pi ) 

 t Proc. Roy. Soc, lxix. (1902) pp. 4G6-70. 



