24 H. HAYS BULLARD 



not expect to obtain a true picture of the granules by the use of 

 an aqueous staining solution on unfixed material. The arrange- 

 ment of the granules is often very irregular in Cresylviolett prep- 

 arations of unfixed material especially if the section is exposed 

 to the action of water previous to staining or left too long in the 

 stain, or if the material is taken from animals following rigor 

 mortis. Under such circumstances granules are absent from por- 

 tions of the fiber and are aggregated in masses within other por- 

 tions of the fiber or beneath the sarcolemma. The blue stained 

 substance, however, is not easily, if at all, soluble in water. Aque- 

 ous solutions of Cresylviolett may also be applied t.o frozen sections 

 of material fixed fresh for two to twenty-four hours in 20 per cent 

 formalin in a 0.75 per cent sodium chloride solution. Such prep- 

 arations show a comparatively uniform arrangement of the blue 

 staining granules corresponding to that of the true interstitial 

 granules of Kolliker. 



It has already been mentioned that the wing shaped processes 

 of Kolliker, which give the granules a stellate appearance, are 

 not stained b}^ Cresylviolett when the section has been previously 

 treated with alcohol. In formalin fixed material the large gran- 

 ules of the pectoral muscles of the pigeon can be stained intensely 

 with Nile blue or faintly with Cresylviolett even after the action 

 of alcohol. The true intersititial granules in the muscle fibers of 

 the dog, cat, rat and rabbit stain with Cresylviolett and for the 

 most part appear to be soluble in alcohol both in fresh material 

 and in formalin fixed material for they cannot be stained when 

 sections have been previously treated with absolute alcohol. 

 When this material has been kept in 20 per cent formalin for sev- 

 eral weeks, the wing-shaped processes and soluble granules seem 

 to have disappeared and can no longer be demonstrated by Cresyl- 

 violett or Nile blue sulphate. Even after prolonged exposure 

 to formalin the true interstitial granules in the pectoral muscles 

 of the pigeon are still readily stained by Nile blue sulphate and 

 faintly colored by Cresylviolett. 



If it be supposed that the alcohol-soluble substance of the true 

 interstitial granules is a form of fat, the fact that it stains with 

 basic dyes n^ay indicate that it is a lipoid or fatty acid. 



