PROTEIN GRANULES. 



45 



now to be examined being those wliicli 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 thej- are more or 

 less soluble in water, and hence 

 require special treatment for their 

 satisfactorj- examination. Colls 

 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 Pfeffer ; namely, to subject the 

 grannies to the action of an alco- 

 holic solution of mercuric chloride, 



b3- which they are rendered insolubte (see 63). The solution 

 is made bj' 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 tliis period, tliej- remain substantially 

 unchanged. The precaution must be taken not to touch with 

 au}' metal the sections after they have been placed in the 



mercuric chloride solution. 

 They must be removed bj- a 

 eamel's-hair brush. 



177. The protein matter 

 of which protein granules 

 consist ma}- 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 ci-ystalline. H,ence in some protein gran- 

 ules we have to distinguish between the inorganic contents, the 



Fig. U. Cells from cotyledons of Vicia sativa, showing protein matters in a finely 

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



Fin. 12. Protein granules from the endosperm of liiciiius communis. The specimen 

 is in oil. H". (Pfetfer. ) 



Fig. 13. Protein granules from the endosperm of Ricinus communis. The specimen, 

 first treated with mercuric chloride in absolute alcohol, is now in water. *^^. (Pfeffer.) 



