SPECIAL METHODS. 2O/ 



renoids behave with these in about the same way as do the 

 crystalloids of the nuclei and the chromatophores. Very 

 -deep staining of them may be obtained by fixing algae with 

 picro-sulphuric acid ( 304) or an alcoholic solution of cor- 

 rosive sublimate ( 310), washing well, and then leaving them 

 at least 24 hours in a .2% solution of acid fuchsin. After 

 washing in water for a quarter of an hour and dehydrating 

 in Schulze's apparatus ( 16), the objects should be trans- 

 ferred to Canada balsam by the aid of Schulze's settling 

 cylinder ( 21). In good preparations only the pyrenoids 

 are deep red, and even the nucleoli are quite colorless. 



363. A simultaneous fixing and staining of chromato- 

 phores and pyrenoids may be obtained more simply by 

 placing the algae in a concentrated solution of picric acid in 

 50$ alcohol, to which a little acid fuchsin is added (about 

 five drops of Altmann's solution, described in 345, to a 

 watch-glass full of the picric acid solution). In this they re- 

 main for two hours or longer, and are then washed for a 

 quarter of an hour in alcohol (not previously in water) and 

 then transferred as quickly as possible to balsam by the aid 

 of Schulze's settling cylinder ( 21). Preparations thus ob- 

 tained appear to keep well, while a gradual fading occurs in 

 those mounted in Vosseler's turpentine ( 27). 



3633. According to the researches of Hieronymus (I, 358), 

 the pyrenoids of Dicranochcete renifonnis appear to have a 

 more complicated constitution. This author states that 

 they consist of a protein crystalloid and a protei'd-like en- 

 velope, while the starch-grains are formed quite independ- 

 ently of the pyrenoids, at any part of the chromatophore. 



The crystalloids are soluble, according to Hieronymus, 

 in boiling water (!), dilute and concentrated caustic potash 

 solution, common salt solution, acetic acid, and hydrochloric 

 acid. After previous treatment with alcohol, its solubility 

 becomes less. After lying for several days in a mixture of 

 one volume of pepsin-glycerine and three volumes of .2% 

 hydrochloric acid, the crystalloids become very transparent. 

 Hieronymus recommends safranin for staining them. 



The envelope is also soluble in concentrated and dilute 



