1887.] 



Presents. 



181 



entirely collected around the nucleus at the centre of the cell, the 

 latter still remains turgid. 



The author is also of opinion that de Vries' view, that the turgidity 

 of the cell is mainly dependent on the presence of certain osmotically 

 active substances in the sap, of an acid nature, requires some further 

 qualification, for his own results agree rather with those of Schwartz, 

 since he finds that turgid cells may possess either an acid or an 

 alkaline sap. Thus, in Drosera itself, the cells of the tentacles have 

 an acid, and those of the petals of the flower an alkaline reaction. 



Finally, the author believes that the property of contractility, 

 which he claims to have established for the irritable cells of Drosera 

 and Mimosa, and for the less specialised cells of Mesocarpus, is a pro- 

 perty which is possessed in a greater or less degree by all the actively 

 living cells which constitute the tissues of plants. The important 

 bearing of these results on all phenomena of movement and growth is 

 sufficiently obvious. The author hopes to deal with the matter in 

 fuller detail in a future paper. 



Presents, November 24, 1887. 



Transactions. 



Berlin : — Physikalische Gresellschaft. Yerhandlungen. 1886. 8vo. 



Berlin 1887. The Society. 



Bern : — Naturforschende Gesellschaft. Mittheilungen. 1886. 8vo. 



Bern 1887. The Society. 



Birmingham: — Mason Science College. Calendar. 1887-88. 8vo. 



Birmingham 1887. The College. 



Bombay: — Royal Asiatic Society (Bombay Branch). Journal. 



Vol. XVIII. No. 45. 8vo. Bombay 1887. The Society. 



Boston : — American Academy of Arts and Sciences. Proceedings. 



Vol. XIV. Parts 1-2. 8vo. Boston 1887; Memoirs. Vol. XV. 



Part 4. No. 5. 4to. Cambridge 1886. The Academy. 



Breslau : — Schlesische Gesellschaft fiir vaterlandische Cultur. 



Jahresbericht LXIV., with Erganzungsheft. 8vo. Bresla 



1887. The Society. 



Brighton : — Brighton and Sussex Natural History and Philosophical 



Society. Annual Report. 1887. 8vo. Brighton. The Society. 

 Brussels : — Academie Rovale de Medecine de Belgique. Memoires 



Couronnes et autres Memoires. Tome VIII. Fasc. 2-4. 8vo. 



Bruxelles 1887. The Academy. 



Academie Rovale des Sciences, des Lettres et des Beaux Arts de 



Belgique. Memoires Couronnes et autres Memoires. Tomes 



XXXVII-XXXIX. 8vo. Bruxelles 1886; Memoires. Tome 



XLVI. 4to. Bruxelles 1886 ; Memoires Couronnes et Memoires 



VOL. XL!Il. P 



u 



