ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 213 



BOTANY. 



A. GENERAL, including the Anatomy and Physiology 

 of the Phanerogamia. 



a. Anatomy. 

 (1) Cell-Structure and Protoplasm. 



Centrosomes in Spermatogenous Cells. * — In opposition to the 

 opinion of Shaw,f Heir W. Belajeff confirms, from a fresh series of 

 experiments, chiefly on the microspores of Ularsilia, the statement that 

 the stainable bodies observed by him in the spermatogenous cells of the 

 Characeae, Filicinese, and Equisetacese, are true centrosomes. As an ex- 

 planation of the non-occurrence of centrosomes in the vegetative cells 

 of Vascular Cryptogams and Phanerogams, the author suggests that 

 probably the morphological and dynamical centre which we call the 

 centrosome may exist in every cell ; but that it is not always the case 

 that a stainable substance is deposited in it which makes it easy to 

 detect in preparations. 



Periplasmic Membrane.:}: — Keplying to the criticisms of Tswett, § 

 Prof. K. Chodat and M. A. M. Boubier maintain their previous position 

 that the periplasmic membrane (parietal utricle) is not a differentiated 

 organ of the cell. The limiting zone of protoplasm is not merely the 

 expression of a superficial tension ; it is the result of a kind of coagu- 

 lation from contact with the liquid medium, the result of physico-chemical 

 reactions on living protoplasm. 



Mannocellulose in Gymnosperms.|| — According to M. G. Bertrand, 

 the woody tissue of Angiosperms (Dicotyledons and Monocotyledons) is 

 composed of four principal , substances, ordinary cellulose, the vasculose 

 of Fremy, a resin probably of a phenol or lignol nature, and the wood- 

 gum, which he terms xylane. In Gymnosperms (Conifers, Cycadeae, 

 aud Gnetacese) the xylane is replaced by a different carbohydrate, 

 mannocellulose, of which, however, the formula is not given. 



(2) Other Cell-Contents (including' Secretions). 



Chlorophyll and its Derivatives. — Herr L. Marchlewski 1f contests 

 many of the conclusions arrived at by Kohl in his researches on this 

 subject ; to which F. G. Kohl replies,** charging Marchlewski with in- 

 accuracies on diverse points. Dr. G. Bode jf also differs from March- 

 lewski in many of his conclusions, and contributes a theoretical and 

 polemical paper on the constitution and properties of phylloxanthin. 



To these criticisms Marchlewski J| makes a final reply, and gives a 

 table of the suggested relationships to one another of the various deriva- 

 tives of chlorophyll. 



* Ber. Deutseh. Bot. Gesell., xvii. (1899) pp. 199-205 (1 pi.). Cf. tbis Journal, 

 1S9S, p. 550. t Cf. this Journal, 1899, p. 58. 



% Journ. de Bot. (Morot), xiii. (1899) pp. 379-83. Cf. this Journal, 1S9S, p. 637. 



§ Cf. this Journal, 1899, p. 498. || Comptes Rendus, cxxix. (1899) pp. 1025-8. 



t Bot. Ceutralbl., lxxix. (1899) pp. 221-2. Cf. this Journal, 1898, p. 438 ; 1S99, 

 p. 404. ** Tom. cit, pp. 223-7. ft Tom. cit., pp. 227-39. 



t% Op. cit., lxxx. (1899) pp. 340-9. 



