METHOD OF ANALYSIS. 93 



to the animal muscles ; we must, however, offer a few remarks on 

 certain points to which we have not been previously able to allude. 

 We refer especially to the examination of the fluid contained 

 in the sarcolemma, and permeating the muscular bundles. We 

 are. unfortunately, unable to procure this fluid free from the liquor 

 sanguinis, and hence we know of no better method to recommend 

 than that adopted by Liebig. It is self-evident that the muscle 

 selected for examination should be fresh, and freed, as far as pos- 

 sible, by means of the scalpel from fat, tendon, membranes, cel- 

 lular tissue, vessels, and nerves ; it should then be finely minced, 

 chopped, or shredded, taking care that no splinters of wood or 

 other extraneous substances are mixed with the object. Accord- 

 ing to Liebig's directions, half of the chopped flesh should be put 

 into an equal weight of water, and after being duly kneaded into 

 a pulpy mass, should be exposed to pressure in a linen strainer. 

 The residue, after pressure, must be again twice kneaded with 

 water and pressed, so that we obtain three extracts from the first 

 half of the flesh. The fluid of the second pressing of this first half 

 is employed for the first extraction of the second half of the reserved 

 chopped flesh; whilst the fluid of the third pressing is used for a 

 second extraction of the second portion, which is then again ex- 

 tracted with pure water. The flesh of fishes and certain amphibia 

 cannot be submitted to pressure in a finely chopped state, as it 

 swells in water into a thick gelatinous mass, which clogs up the 

 pores of the linen. According to Liebig, we must here have recourse 

 to the process of displacement. The muscular substance of frogs dif- 

 fers from that of fishes ; it admits very readily of being pressed, and 

 is, therefore, peculiarly well adapted for experiments of this nature. 

 The expressed acid fluid, which is either turbid, or at all events 

 opalescent from the presence of fat, must be treated in the water- 

 bath until all the coagulable matters separate from the solution. 

 The expressed fluid, after the removal of the coagula by filtration, is 

 either of a faint reddish hue, or nearly colourless. The evaporation 

 requires to be conducted with extreme caution, and Liebig has drawn 

 attention to the circumstance that the fluid is disposed to assume 

 a brownish colour during the process of evaporation, in consequence 

 of the presence of the free acid. On this account Liebig recom- 

 mends the addition of baryta water, so long as any precipitate is 

 deposited, not only for the purpose of neutralising the fluid, but 

 also that the phosphates may be removed as far as possible. The 

 next step is to crystallize the greater part of the creatine con- 

 tained in the fluid, according to the method indicated in vol. i, 



