ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 315 



and without food for fourteen days after the extraction of the style. A 

 new style begins to be formed, but it does not develop far. The 

 typhlosoles supply the material for the substance of the crystalline style, 

 and the shorter cells with strong ciha assist in moulding it into 

 cylindrical form and at the same time rotate it and push it into the 

 stomach. J. A. T. 



Muscles of Bivalves.— R. Anthony {Arch. Zool. Exper., 1919, 58, 

 Notes et Revue, 1, 1-10, o figs.). In the adductor muscles of Lamelli- 

 branchs there are two kinds of fibres — {(t) smooth fibres with a high 

 coefficient of shortening, used in slow sustained movements (the nacreous 

 portion) ; and {h) fibres with a co-efficient of shortening not so high, 

 associated with rapid and less sustained movements— which sometimes 

 show distinct striations and sometimes an apparently quite different 

 lozenge-shaped structure, occurring in many Invertebrates. According 

 to Anthony, the fibres with the lozenge structure are fixed stages of the 

 transition between smooth and striped muscle, and are associated with 

 increasing rapidity of movement. This is opposed to Marceau's view, 

 which interprets the lozenge-like pattern as due to the intercrossing of 

 two layers of spiral fibrils. Anthony points out that the transition may 

 be seen in one fibre, and maintains that the theory of helicoidal fibrils 

 does not work. J. A. T. 



Shell of Cockle.— C. L. Walton {Report Lancashire Sea-Fisheries 

 Laboratory, 1911), 28, 17-50). Concentric grooves denote periods during 

 which growth has ceased, notably winter, and their number increases in a 

 regular manner along with the increase in the size of the shell. Variations 

 in food supply and other environmental conditions also affect the shell. 

 Large forms showed seven to ten grooves. Tliere is no correlation 

 between the number of ribs (twenty to twenty-seven) and the age and 

 size of the shell. In the smallest specimens examined (0*98-1 "50 cm. 

 in dorso-ventral diameter) the number of ribs varied in exactly the same 

 •degree as the largest (;^> • 50-1 -11 cm.). J. A. T. 



Arthropoda. 

 a. Insecta. 



Isle of Wight Disease in Hive Bees.— John Rennie and Elsie 

 J.. Harvey {Scottish Joiirn. Ar/ric, 1919, 2, 1-13). The presence of 

 this disease in a stock is manifested by the inability of the worker bee to 

 fly. They loiter on the ahghting board, on the ground, on grass. They 

 gather in clusters and lie almost motionless. Individual bees, once stricken 

 with the disease, do not recover, but a remnant of a badly affected stock 

 was kept alive for two months in the autumn. Within the hive the 

 smitten bees do little work, feed little, show lack of co-ordination of 

 fore- and hind-wing, and often fall from the frames. Very generally the 

 hind-gut becomes dilated with undischarged faeces, which is largely due 

 to the incapacity of the bee for flight, defecation normally occurring 

 when on the wing. It is suggested that infection takes place most 

 readily through contact with sick bees, in the early adult phase before 



