PROTEIN GRANULES. 



45 



now to be examined being those which take the form of more or 

 less regular grains. These which are known as 



176. Protein granules may be either independent, or asso- 

 ciated with other substances. In 

 nearly all cases the}- are more or 

 less soluble in water, and hence 

 require special treatment for their 

 satisfactory examination. Cells 

 supposed to contain them may be 

 placed for examination in any fixed 

 oil, and the granules will remain 

 unchanged. A more practicable 

 method of treatment is suggested 

 by Pfefler ; namely, to subject the 

 granules to the action of an alco- 

 holic solution of mercuric chloride, 

 by which they are rendered insoluble (see 63). The solution 

 is made by dissolving one part of mercuric chloride (corrosive 

 sublimate) in fifty parts of absolute alcohol ; in this solution 

 the thin sections of seeds, etc., suspected of containing pro- 

 tein granules, must be kept for at least twelve hours. Upon 

 removal to water, after this period, they remain substantially 

 unchanged. The precaution must be taken not to touch with 

 any metal the sections after they have been placed in the 



mercuric chloride solution. 

 The}' must be removed by a 

 camel's-hair brush. 



177. The protein matter 

 of which protein granules 

 consist may be wholly with- 

 out definite shape, or a por- 

 tion may assume somewhat 

 the form of crystals. The 

 latter have been called pro- 

 tein crystals or crystalloids, and they are generally associated, 

 in the granules of which they form a part, with inorganic matters 

 either amorphous or crystalline. Hence in some protein gran- 

 ules we have to distinguish between the inorganic contents, the 



FIG. 11. Cells from cotyledons of Vlcia sativa, showing protein matters in a finely 

 divided state, intermingled with starcli-granules. (Schmidt.) 



FK;. 12. Protein granules from the endosperm of Ricinus communis. The specimen 

 is in oil. *?. (Pfetter ) 



FK; 13. Protein grannies from the endosperm of Ricinns commnnis. The specimen, 

 first treated with mercuric chloride in absolute alcohol, is now in water. <?. (Pfefter.) 



