ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 465 



size. The nuclei are large, irregular, and have one or more nucleoli ; 

 there may be several in a single cell. In the rare cases where fertilisa- 

 tion has taken place, the albumen then formed is identical with that 

 found in Smyrna figs. It would appear that the development of 

 parthenogenetic albumen is dependent upon the deposition of the eggs 

 of the Blastophagus in the female flowers, for Capri figs which had not 

 been visited, withered before maturity. The impulse given by the visit 

 of the insect replaces that given normally by fertilisation, and upon it 

 depends the future growth of the ovule, pericarp, and albumen. 



Physiology. 

 Chemical Changes. 



Colouring Matter of Chlorophyll.*— L. Marchlewski and J. Robel 

 contribute a preliminary note upon their researches in connection with 

 the colouring matter of chlorophyll. The authors have treated an 

 80 p.c. alcoholic solution of chlorophyll with gaseous hydrochloric acid, 

 and have succeeded in obtaining a black-brown sediment which can be 

 used in the preparation of various chlorophyll derivatives. This sedi- 

 ment, to which the name phyllogen is given, appears to be identical with 

 phgeophytin— a substance lately prepared by Willstatter, by the action 

 of oxalic acid "on crude chlorophyll solutions — since the physical and 

 chemical properties of both are alike. The authors consider, however, 

 that further investigations are necessary, since the composition of 

 various chlorophyll derivatives is so similar, that constancy of com- 

 position does not prove homogeneity. 



Change of Colour and Emptying of Decaying Leaves. — M. 

 Tswettf has made experiments upon decaying leaves, and considers that 

 there are two stages in their autumn colouring : shades of red or yellow 

 prevail while the leaf is dying, while grey, brown, and black indicate 

 that the leaf is dead. During the breaking-down and disappearance of 

 plastic materials, the leaves remain fresh and turgescent, even to the 

 epidermal cells, and the experiments show that both epidermal and 

 mesophyll cells retain the semi-permeable plasmatic membrane. Even 

 after leaf-fall, cell-life may be retained for a considerable time. In the 

 second stage the leaves lose their turgescence, owing to a soluble, 

 oxidising enzyme, which is prevented from acting in living leaves 

 through the osmotic limits of the cell-contents. The author confirms 

 the old opinion that the more important constituents of the ash and the 

 nitrogen compounds return from the leaves to the mother-shoot before 

 leaf -fall. Most of the experiments made with regard to the emptying 

 of leaves are unsatisfactory, and only the re-transmission of the nitrogen 

 is at present fully established. 



In a second paper $ the author states that yellow leaves contain only 

 traces of normal colouring matters, their colour being due to a new 

 pigment, termed "autumn xanthophyll." The latter is probably a 



* Bull. Acad. Sci. Cracovie, x. (1907) pp. 1037-9. 

 t Ber. Deutsch. Bot. Gesell., xxvi. (1908) pp. 88-93. 

 X Tom. cit., pp. 94-101. 



Aug. 19th, 1908 2 I 



