Mussel Scale. 



507 



farm, does not lend itself to industrial conditions. It has also 

 long been known that nitrogen may be induced to unite with 

 oxygen through [the agency of electricity, but, so far, this 

 process is hardly beyond the stage of a laboratory experiment. 

 Recently attention has been given to fixation through the 

 agency of calcium carbide, and a description of the process, 

 with an account of experiments conducted with the resultant 

 substance on various crop-plants, were communicated on the 

 1 8th of February to the Manurial Section of the German 

 Agricultural Society by Prof. Gerlach, of Posen. 



The'nitrogen so fixed may be used either as calcium cyanamid 

 or as ammonium sulphate. The experimental results in some 

 cases are very favourable to the new substance, while in others 

 they are less so. Evidently there is still much to learn with 

 regard to the conditions under which it may be most advan - 

 tageously employed, but there can be little doubt that the 

 report in question marks a long step forward. 



[Mitt. Deut. Land, Gesell. Feb. 20th, 1904.] 



The Mussel Scale. 

 {Mytilaspis pomonim. Bouche.) 

 The Mussel Scale (Alytilaspis pomoruni), or Oyster-shell Bark 

 Louse, as it is sometimes called, is found chiefly on apple, but 

 also [on pear, currant, plum, hawthorn and blackthorn. This 



Fig. a, Female Mussel Scale, dorsal view ; Fig. b, ventral view ; 

 Fig. c, Male Scale.* 



* From \ First \Report on Economic ^ Zoology , British Museum, National 

 History Department. 



