210 



have been borne out by subsequent observations. Water 

 extractions carried out in a Soxhlet apparatus upon mussels 

 which had performed the railway journey from Morecambe, 

 and subjected to the Mohr-Bertrand method of volumetric 

 estimation for glucose, after precipitation of the proteids in the 

 solution with basic lead acetate, gave no reaction. Yet the 

 water extraction is fairly effective, as is shown by the fact that 

 in the sample for April 1922, the solution, after inversion, 

 gave a glycogen return of 0-862 % on the wet substance, 

 whereas a glycogen estimation by Pfliiger's short method gave a 

 value of 0-992 % which is not much higher. In this connection 

 it is interesting to compare the results of glycogen estimations 

 made from the wet flesh, and then from the dried powder of the 

 same sample : the following results are expressed as per- 

 centages on the wet substance, and were obtained by Pfliiger's 

 method except where otherwise stated. 



The 'percentage of Glycogen in the ivet substance — 



Calculated from wet flesh. Calculated from dry powder. 



June 23, 1921 4095 2-733 



Nov, 17, 1921 3-844 0-704 (water extraction) 



Dec 16 19-^1 ''•699 ' ^ ""^ 



' (1 -252 (water extraction) 



Extractions from the dry material of these samples were 

 also carried out by stirring with 0-4 % hydrochloric acid and 

 repeated decantmg through filter paper. The solution 

 obtained failed to reduce Bertrand's solution. This suggests 

 that the glycogen may be broken down into other material 

 than glucose. 



The question of variation in the quantity of glycogen 

 seemed of such importance that, in spite of the labour entailed, 

 estimations were performed for the later samples. Pfliiger's 

 method was adopted, and after inversion the glycogen was 

 estimated as glucose, by the Mohr-Bertrand, or Benedict's 

 method. Both of these give results which are strictly com- 



