80 SCIENCE PROGRESS. 



grains he observed that the larger side of the grain is 

 opposite to the position of the leucoplast, instead of being 

 in contact with it. In Maranta arundinacea he observed 

 cases where the starch grains originated in contact with a 

 leucoplast. but subsequently became free from it, and after- 

 wards grew while embedded in the protoplasm. 



It appears therefore most probable that the importance 

 of the plastid has been somewhat exaggerated in connection 

 with the development of starch grains, and that although 

 its influence is very generally exerted, the protoplasm itself 

 is capable of forming the starch grain as it is other con- 

 stituents of the ordinary cell contents. 



Another point of some interest arises in connection with 

 the plastids, whether coloured or not. It has been generally 

 held that they are not differentiated anew from the proto- 

 plasm at the seat of their appearance, but are derived from 

 others by ordinary fission. On this hypothesis one at least 

 must be present in the fertilised egg-cell. No such struc- 

 ture appears in the pollen grain, or the pollen tube, and 

 hence all the plastids of a plant must be derived from 

 its female parent. This seems an anomaly difficult to 

 explain. 



Glycogen as a reserve material is especially charac- 

 teristic of fungi, in several of which it has been detected. 

 Usually the reserves in fungi are but slight, and take 

 various forms, especially oil, but sometimes cellulose and 

 glycogen, the latter occurring with the other two or one of 

 them. The reserve materials of fungi have chiefly been 

 studied in connection with the sclerotia, particularly in the 

 case of ergot {Claviceps purpurea). In the sclerotia de- 

 scribed by Errera (31) as Sclerotium stipitatwn, a mass of 

 tissue exists consisting of small thin-walled, rounded cells 

 mixed with long fibres, whose cavities are nearly obliterated. 

 The former are filled with glycogen. When the sclerotia 

 germinate the glycogen diminishes in amount, and in some 

 form or other passes into the new hypha. The form in which 

 it travels has not been ascertained, but it is probably a 

 form of sugar as in other carbohydrate migrations. In the 

 young hyphae temporary accumulations or transitory re- 



