102 pringsheim's researches on chlorophyll. 



a normal formation of oil-globules ])rocee(ls in them, and he 

 concluded that they must regularly pass out of the same. 

 But besides those mentioned, many other plants are known 

 in which no starch is found and oil-globules occur in the chlo- 

 rophyll-corpuscles. Thus, of plants without starch we have 

 Selaginella, Cycas, Stratiotes aloides, Lilium Martagon, Olea 

 europa.a, and Begonia. The small refractive oil globules of 

 the bauds of Spirogyra have been long known, and in 

 Characece the chlorophyll-corpuscles possess oil globules in 

 addition to or instead of starch, which pass out of them in 

 the course of development. 



Starch and oil have, from their easy recognition, been often 

 hitherto regarded as the only products of the function of the 

 chlorophyll-corpuscles. In some cases, when neither starch 

 nor oil has been found, an(i abundance of glucose or mannite 

 has been discovered in the leaves of a plant, these substances 

 have been considered as the product of the chlorophyll-cor- 

 puscles. But neither starch, oil, nor sugar are the only 

 products, nor, indeed, the only visible ones. Pringsheim in 

 one case observed iiighly oxidised bodies of the group of 

 organic acids directly formed in the chlorophyll-corpuscles, 

 and this makes it probable that of the bodies hitherto con- 

 sidered to be fat or oil-drops many consist of substances of a 

 very different character. Again, in Mesocarpus scalaris} at 

 all stages of development and in every cell, there may be seen 

 numerous (almost covering the chlorophyll-plate) small, oil- 

 like, glistening globules of different sizes, and very iike the 

 small oil-globules in the bands of Spirogyra, which, as they 

 disappear on the addition of alcohol and ether, might at first 

 be regarded as fat or oil-globules. They are clearly formed 

 in and secreted by the chlorophyll-plate, and pass out from 

 it into the protoplasm of the cell These are not oil- 

 globules but vesicles with a resisting pellicle, enclosing a 

 content in greater or less part consisting of tannin. They 

 may be termed tannin-vesicles (fig. 20 c). The dark 

 coloration and coloured precipitate formed with iron salts, 

 potassium bichromate, and with Millon's reagent, conclu- 

 sively indicate their nature (fig. 1^2). The form of these 

 vesicles is easily destroyed by slight warmth, mechanical irri- 

 tation, or any decompostion which will end in the death of 

 the cell, and when destroyed the contents disappear, mixing 

 with the cell-sap, and the pellicle is then indistinctly seen 

 appressed to the chlorophyll-plate, and giving its surface a 

 netted or froth-like aspect (fig. 21). 



^ Tliis species was determined from specimens just commencing to con- 

 jugate. It is the form generally known as Mougeotia genujiexa. 



