ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 457 



suffering from defective nutrition ; application of manures, especially 

 basic ones, is recommended as a remedy. 



Chemotropism of Fungi.* — Harry R. Fulton gives a preliminary 

 sketch of the views held and the results obtained by previous workers 

 in this field of research. He carried out his own experiments with some 

 fourteen fungi, parasitic and saprophytic. He employed capillary tubes 

 filled with certain chemical substances, to test the influence of the 

 substances on germinating spores. He also used the mica-plate method, 

 piercing the plate with holes, and coating the under-surface with gelatin 

 mixed with the test solution. From all these experiments he concluded 

 that positive chemotropism scarcely exists. All of the fungi tested 

 showed a tendency to turn away from a medium in which hypha? had 

 grown previously. Various fungi showed positive hydrotropism, while, 

 in some cases, an overabundance of moisture caused a negative reaction. 

 Fulton considers that the drying up of the moisture in which spores 

 have germinated on the leaf, may be the factor that impels growth 

 towards the stomata. 



M. Racibowski f has grown Aspergillus niger in solutions containing 

 various chemicals, but chemomorphism, he found, was induced only by 

 thiosulphate, chloroform, and iodine. In thiosulphate solution the 

 fungi is not poisoned, but no spores are produced. The conidiophore is 

 formed, but sulphur drops congregate in the end of the hyphas and 

 hinder further growth. The plants grown in chloroform fructified to 

 four generations. The growth of the hyphse was, however, considerably 

 affected ; swollen cells were found full of protoplasm, the ends of the 

 hyphae were slender, and bore repeatedly forking branches. Spores were 

 numerous, and the sterigmata of old conidiophores became globose at the 

 ends. In weak solutions of iodine, growth was not materially altered ; 

 in a stronger mixture, no spores were formed, and abnormal growths of 

 the filaments took place. Very large cells were found filled with pro- 

 toplasm, and the membrane gradually thickened. Iodine reacted 

 similarly on the growth of Thamnidium elegans. 



Chemical Changes. 



Behaviour of Plants towards Aluminium.J — W. Rothert finds that 

 plants take up aluminium in varying quantities if in suitable form, such 

 as soluble salts and certain insoluble ones such as phosphate. The 

 whole or greater part is retained in the roots. The small amount of 

 suitable salts present in soil accounts for the presence of so little 

 aluminium in plants. Soluble salts act injuriously except in very dilute 

 solutions, also in specifically large quantities, yet plants often take up 

 surprisingly large quantities of soluble salts, if the anion has no injurious 

 effects (e.g. chloride). In some cases small quantities of aluminium 

 salts exert a stimulating effect on plant development. 



Aluminium can only be taken out of solution into tissues up to a 

 fixed limit of concentration, which is independent of the concentration 



* Bot. Gazette, xli. (1906) pp. 81-108. 



t Bull. Acad. Sci. Cracovie, No. 10 (1905) pp. 764-78. See also Bot. Ceutralbl., 

 ci. (1906) pp. 499-501. % Bot. Zeit., lxiv. (1906) pp. 43-52. 



An/, loth, 1906 2 h 



