14 



A and B). They are small colourless granules, very refractive in appearance, 

 and their outward form is either round or subangular. They give reactions 

 for both nitrogen and phosphorus, and consist of albuminous protein in 

 a crystalloidal form. They swell up and dissolve in 0'5 per cent, hydro- 

 chloric acid, and also in dilute nitric or sulphuric acids. In artificial gastric 

 juice they are completely digested in about one hour. They give no reaction 

 for iron. They have a special affinity for picro-carmine, stain blue-violet 

 with Ehrlich's hasmatoxylin, a faint blue with Delafield's haematoxylin, 

 and a bright red after a prolonged treatment with an alcoholic solution of 

 eosin. Cyanophycin granules entirely disappear when the albumen- 

 consumption of the protoplast is great, and their number and presence 

 depend largely upon physiological conditions. They are absent in dividing 

 cells, and they gradually disappear in the dark or when the vitality of the 

 protoplast is impaired. They occur in large numbers in spores, but are 

 consumed during the germination of the spores. There is little doubt 

 that cyanophycin granules constitute a reserve food of an albuminous 

 character. 



(3) Mucus-vacuoles. These are the slime-balls of Palla and the slime- 

 vacuoles of Hegler. They are difficult to distinguish from cyanophycin 

 granules, but are larger, and to some extent they are differentiated by stains. 

 It seems likely that they contain a substance allied to mucin, which is 

 insoluble in hydrochloric acid, stains a red-violet 1 with ha?matoxylin, and 

 red with eosin. This substance is apparently a glucoprotein and gives a 

 carbohydrate chemical reaction. Mucus-vacuoles cannot always be detected, 

 and when present they mostly occur in the zone of cytoplasm surrounding 

 the primitive nucleus, although they may extend further outwards. 



(4) Glycogen and Sugar. Glycogen was first mentioned by Biitschli as 

 occurring in the Myxophycean cell, and it was shown to exist by both 

 Hegler and Kohl. Gardner proved its existence experimentally, and also 

 that sugar was present in many of the Blue-green Algse. Aqueous extracts 

 of many kinds of Myxophycese after pulverization with fine sand readily 

 reduce Fehling's solution, and it seems probable, therefore, that sugar is the 

 first product of photosynthesis in these plants, and that some of this sugar is 

 converted into glycogen as a carbohydrate reserve. 



Starch is entirely absent from the Myxophycese. 



(5) Oil. Minute oil-drops may occur in the cytoplasm of many forms 

 of the Blue-green Algse, and can be detected by osmic acid. They have also 



1 Mucus-vacuoles are said by Phillips ('04) to stain blue with Delafield's hienmtoxylin, but it 

 is necessary to point out that the colour of stained granules of this character is very misleading. 

 A small refractive sphere of dense mucus stained with haernatoxyliu may appear of various 

 shades of red, blue or violet according to the focus and the colouration of the protoplast in 

 which it is embedded. 



