Guilliermond - Atkinson 



206 — 



Cytoplasm 



a substance related to glycogen which is sometimes encountered in 

 bacteria and Phytoflagellates as granules which stain brown with 

 iodine. 



Fig. 143. — Iris germanica. Chondrio 

 somes (M) and plastids (P) in the form 

 of chondrioconts in epidermal cells of the 

 leaf. 1, living material. 2, Meves' 

 method with acid fuchsin. 3, Regaud's 

 method. Lipide granules (Gl) very 

 refractive in 1, blackened by osmium in 

 2, not preserved in 3. 



Protein crystalloids are sometimes encountered also in the cyto- 

 plasm. In the tubers of white potatoes, for example, a crystalloid 

 of protein is found in the cytoplasm of most of the cells. It is 

 rather large and cubical in shape and is deeply stained by iron 

 haematoxylin. Similar variously-shaped crystalloids (spindle- 

 shaped, cubical etc.) often exist in the plectenchyma of the carpo- 

 spore of the Agaricaceae and in the mycelium of Spermophthora 

 gossypii, as well as in the Mucors, in which they have been de- 

 scribed under the name of crystalloids of mucorine (van Tieghem) . 



It is suitable also to mention a voluminous spherical inclusion 

 which is present in the cytoplasm of certain special cells of vari- 

 ous Rhodophyceae. This is called an iodine reservoir (Fr. 

 ioduqiie), is very refractive and occupies the major part of the 

 cell. Its nature is still unknown but it seems to contain iodine 

 which is free or in the state of an unstable compound released 

 when the reservoirs are broken. 



Attention has been called in the same algae to cells called hro- 

 mine reservoirs (Fr. bromuques), which rather analogously contain 

 bromine. Let us mention furthermore that there exist in the proto- 



