320 TRANSACTIONS AND PROCEEDINGS OF THK [Sess. lxiv. 



hand, those of Equisetum germinated equally in light and 

 in darkness. 



Passing from this brief historical outline, we now turn 

 to the subject with which we are more immediately con- 

 cerned. 



Hyclrocharis Morsus-Rancc, as is well known, propagates 

 very freely in a vegetative manner, by means of subaqueous 

 runners arising in the axils of the lower leaves, and bearing 

 at their free extremities buds which at once develop into 

 new plants. These, as soon as their first leaves have been 

 expanded, and loug before separation from the parent, 

 produce new runners, which repeat the process so rapidly 

 that in a short time a considerable area becomes entirely 

 covered with young individuals, all united to one another 

 and to the original plant by more or less elongated branches. 

 This process of vegetative propagation is continued through- 

 out the whole of summer, but in autumn the buds at the 

 extremities of the last formed runners cease to give rise 

 directly to new plants, and undergo structural modifica- 

 tions of such a nature as to enable them to serve as resting 

 organs. The axial portion becomes greatly thickened, and 

 although the protective stipular appendages of the outer 

 leaves are as fully developed as in the summer buds, the 

 leaves themselves, and especially their laminar portions, 

 remain in a rudimentary condition. 



Large quantities of food materials are stored in the 

 swollen stem, and its cells become crowded with small 

 compound starch grains, each composed of three or four 

 individuals arranged in a tetrahedral manner. That, 

 however, no soluble carbohydrates are present, may be 

 assumed from the failure to obtain any reaction with 

 a-naplithol sulphuric acid, or with thymol sulphuric 

 acid, until sufficient time has elapsed to allow of the 

 acid setting up hydrolysis of the starch, etc. 



No oils or resins are distinguisliable, and no aleurone 

 grains or solid reserve proteids can be recognised, but all 

 the cells are completely filled, in so far as they are not 

 occupied by starch, with a clear, somewhat refractive fluid, 

 which, as it entirely and at once disappears from cells 

 injured in the process of section cutting, is ap])arently 

 freely soluble in water. When, however, thick sections, 



