SPECIAL METHODS. 22$ 



alkalies is especially remarkable. These bodies remain 

 almost unchanged in concentrated sulphuric, hydrochloric, 

 and nitric acids, and in glacial acetic acid, according to 

 Overtoil (II, 4). Cold caustic soda also fails to attack them, 

 but on boiling in this solution, the spiny envelope gradually 

 disappears and the interior assumes a spongy structure. 



399. It may also be remarked that Overton has found in 

 the cells of Nitella syncarpa, besides these acanthospheres, 

 vesicles as clear as water which show the same chemical re- 

 lations as they ; and intermediate stages between the two 

 bodies were to be found. In the species of Chara that he 

 studied, Overton found only such spineless bodies ; these 

 are very probably identical with the strongly staining bodies 

 recognized by the writer in the cells of a species of Chara 

 not definitely determined, after fixing with nitric acid and 

 staining with acid fuchsin (cf. Zimmermann II, 51). 



13. Starch-grains and Related Bodies 

 a. Starch. 



400. The chemical composition of starch corresponds to 

 the formula C 6 H ]0 O 5 ; but it is not yet determined whether 

 we have to do with a completely uniform compound in the 

 starch-grains or not. 



The form of starch-grains shows the greatest diversity in 

 different plants. But in a given organ of the same species 

 of plant, only slight variations are observed, except such 

 as are due to the different stages of development of the 

 grains. Some of the characteristic forms of starch-grains 

 are shown in Fig. 53. Figures I, III, and V represent 

 simple 'grains from Canna, Lathrcza, and Euphorbia. The 

 last, two sorts are especially distinguished by their charac- 

 teristic form. Figure IV shows a cell from the horny part 

 of the endosperm of corn, in which the starch-grains lie 

 almost in contact. Figures II and VI, finally, show the so- 

 called compound grains of Beta and Smilax. The former 

 consist of an immense number of component grains. 



401. The larger starch-grains show usually a more or less 



