ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 491 



3. The undulating nutation is promoted by the exclusion of the 

 action of gravity from one side, and the cutting off of light, and passes 

 gradually into circumnutation. 



4. The irregular nutations of Vicia saliva and Pisum sativum are 

 connected with a retardation of the growth in length, and a relative 

 acceleration of the transverse growth. 



5. Monocotyledons also possess the power of nutation during 

 germination. 



Influence of Light on Geotropism.* — Dr. E. Stahl combats the 

 ordinary statement that light, in itself, has no direct influence on 

 geotropic organs. His observations, made on the rhizomes of Adoxa 

 MoschateUina and other plants, have convinced him that light 

 strengthens the geotropism of secondary roots, while on the other 

 hand their growth in length is retarded. He finds that the under- 

 ground runners or stolons of this plant grow in a horizontal direction 

 in the dark, while under the influence of light they grow vertically or 

 obliquely downwards ; and an alternation of light and darkness 

 causes corresponding changes in direction in the same organ. 



Peptonizing Ferments in Secretions, j — Dr. A. Hansen has con- 

 firmed previous statements with regard to the presence of a pepto- 

 nizing ferment in the latex of Ficus Carica. The effect on fibrin is 

 precisely the same as that of digestion by pepsin ; and milk is coagu- 

 lated by it in the same way. The precipitation of the latex by 

 alcohol produces a white precipitate which assumes a light brown 

 colour in the drying bath, and is of a resinous nature. Triturated 

 with water, it produces a milky fluid which is not so emulgent as the 

 original latex, but coagulates milk in the same way. The latex also 

 produces the diastatic reaction of the conversion of starch and 

 glycogen into sugar. A syrup of dried figs has the same peptonizing 

 property as the latex, as also has the secretion of the pitchers of 

 Nepenthes, and the papayotin prepared from Carica Papaya ; but no 

 similar eifect could be obtained from the latex of EuphorbiacesB, 

 Papaver somniferum, Taraxacum, Scorzonera, or Chelidonium. 



The cause of the sweetening of potatoes by frost is stated by 

 Hansen to be that a long period of cold prevents the consumption of 

 sugar by respiration, while the activity of the ferment in producing 

 sugar continues. It is not the immediate result of rapid freezing. 



B. CRYPTOGAMIA. 



Cryptogamia Vascularia. 



Apospory in Ferns— Singular Mode of Development in Athyrium- 

 Filix-fcemina.J — The discovery of apospory by Mr. C. T. Druery in the 

 varieties of this fern known as plumosum-divaricatum and clarissimum, 

 is now published in detail. He describes three forms of the pheno- 

 menon, termed by the author "proliferation," viz.: — (1) Bulbils of 



* Ber. Dcutseh. Bot. Gesell., ii. (1884) pp. 383-97. 

 t SB. Phys.-med. Gesell. Wiirzbursi-, 1884, pp. 106-9, 121-2. 

 X Journ. Linn. Soc. (Bot.), xxi. (1885) pp. 354-60, 360-8 (2 pis.). See this 

 Journal, ante, p. 99. 



