NOTES AND ABSTRACTS. 



739 



better, is the variety imperialis. There is a golden-leaved variety (aurca), 

 which, though not one of the best of golden-leaved trees, is useful because 

 of the situations in which it can be grown. — E. T. G. 



Alder Disease. By Dr. Appel (Nat. Zeit. Land-Forst. ii. pp. 313- 

 320 ; 3 figs. ; 1904). —Numerous Alders (Alnus glutinosa) died in groups 

 in plantations in Poinerania. A fungus (Valsa oxy stoma, already known 

 to attack Alder) was found on all diseased trees. The bark becomes 

 discoloured in strips, generally beginning near a broken branch or other 

 wound. Infection of healthy Alders was unsuccessful. Inquiry showed 

 prevalence of spring-frosts, and a dry period of years from 1899 to 1902, 

 which, coupled with drainage operations, had made the soil very dry. 

 Garden experiments confirmed that Alders grown with too little water 

 became attacked by the same fungus. The author therefore concludes that 

 the trees were weakened by lack of water and by spring-frosts. He points 

 out that Alder plantations may suffer from overdraining ; in dry seasons 

 water may require to be supplied. He states that stool-shoots produce 

 stronger trees than seedlings. — W. G. S. 



Algae : A new Rhododermis. By F. Heydrich (Beih. Bot. Cent. 

 xiv. pp. 243-246; 1 plate). — A new species, B. Van Heurckii, is here 

 described. It was discovered on the leaves of Zostcra maritima in 

 St. Brelade's Bay, Jersey, and forms small dark incrustations about 1 mm. 

 thick, covering the edges of the Zostcra leaves. — G. F. S.-E. 



Algae and Bacteria in Water Supply— to destroy. By Geo. F. 

 Moore and Karl F. Kellerman (U.S.A. Dep. .Agr. Bur. PI. Inch, Bull. 

 No. 64, May 1904). — Assumes the importance of maintaining all public 

 water supplies in the highest degree of purity. The disagreeable 

 odours and tastes so often present are due almost exclusively to Alga? 

 which are widely distributed, and many reservoirs have been rendered 

 unfit for use in consequence. Methods already known for removing the 

 odours and tastes caused by Alga? have proved unsatisfactory, either 

 because of expense or failure to achieve their object. It is proposed to 

 submit a new, cheap, harmless, and effective method for ridding public 

 water of these pests. It has been found that copper sulphate in a dilution 

 so great as to be colourless, tasteless, and harmless to man is sufficiently 

 toxic to the Alga? to destroy or prevent their appearance. 



At ordinary temperature one part of copper sulphate to 100,000 parts 

 of water destroys typhoid and cholera germs in from three to four hours. 



Since the selective toxicity of sulphur sulphate renders it fatal to 

 pathogenic forms peculiar to water, while the saprophytic or beneficial 

 bacteria are unaffected, the method is particularly well adapted for this 

 purpose. Definite knowledge as to what organisms are present, con- 

 stitution of water, temperature, and other important facts are necessary 

 before it is possible to determine the proper amount of copper sulphate to 

 be added. 



No rule for determining the amount of copper sulphate to be added can 

 be given. Each body of water must be treated in the light of the special 

 conditions. — M. G. G. 



