222 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



total solids, and the substances that are removable by extraction with 

 alcohol, ether or \tater were very much reduced. Other substances, 

 such as lipoids, proteids, etc., are discussed and the results given. 

 Finally, they state that there is progressive decrease of the acid-content, 

 and a large increase of alcohol-content in the tissues. 



Growth of Fungi in Concentrated Solutions." — As a result of 

 experimental cultures and research, L. A. Hawkins has found that 

 parasitic fungi are able to grow in relatively high concentrations of salts 

 and sugars, higher even than the concentrations present in the cell-sap 

 of the host-plant. A large selection of parasites were tested, including 

 Fusarium, Rhizopus nigricans, Sphaeropsis malorum, etc. 



Altitudinal Range of Forest Fungi. f — Most of these, as observed 

 by J. R. Weir, have a very great range, from sea-level to the extreme 

 limit of timbered zones, though they are less abundant on the heights, 

 and though certain species " predominate in particular forest zones or 

 types." The altitude also affects the form and structure, etc., of the 

 fungi, especially of certain timber sporophores, but may not materially 

 influence their development within the substratum. 



Apple-rot Fungi in Relation to Temperature. J — C. B. Brooks 

 and J. S. Cooley have conducted a series of cultural studies of Alternaria 

 sp., Botrytis cinerea, Fusarium radicicola, Sphxropsis malorum, etc., on 

 apples at varying temperature. They give a resume of similar researches 

 undertaken by previous workers, and then describe in detail their own 

 results. 



All the fungi grew at 0°, except Fusarium and Glomerella, but with 

 most of the fungi the initial incubation stages of growth on the fruits 

 had been more inhibited by low temperatures than the later ones, which 

 shows the risks run when storage is unduly delayed ; but there is great 

 variation according to the prevalent fungus, and the variety and maturity 

 of the fruit. 



Citrus Canker. §— Frederick A. Wolf describes a disease of Citrus 

 recently introduced into the citrus-growing sections oi the Gulf Coast 

 States. The attack is a very severe one, many varieties and species being 

 affected, and probably none are immune. Grape-fruits are especially 

 liable to injury, but oranges, lemons, and limes are also susceptible to 

 the disease. The primary cause of Citrus canker is a bacterial parasite, 

 Pseudomonas Citri, and a full account is given of the development of the 

 bacterium and of its effect on the host-tissues. Fungi belonging to the 

 genera Fhoma, Fusarium, and Glwcosporium have also been isolated 

 from Citrus cankers. Fhoma sp. was the most active in the disin- 

 tegration of the tissues ; it has been described as Fhoma soda sp. n. The 

 destruction of diseased trees and the observance of proper sanitary 

 precautions are strongly advised. 



* Journ. Agric. Eesearch, vii. (1916) pp. 255-60. 



t Mycologia, x. (1918) pp. 4-14. 



X Journ. Agric. Research, viii. (1917) pp. 127-63 (6 pis. and 25 figs.). 



§ Journ. Agric. Eesearch, vi. (1916) pp. 69-99 (4 pis. and 8 figs.). 



