170 THK PHENOMENON OF 



boundary structure of the cell-mass (the portion of con- 

 tents becoming individualised into a cell), and in this 

 case, just like the coat of the gonidium of Vaucheria, 

 claim may be made to the title of primordial utricle. 

 Thus, in the Characese we find a mucilaginous layer, 

 thicker or thinner in proportion to the age of the cell, in 

 circulating motion ; but outside the circulating mucilage 

 exists a motionless soft coat, to which are attached the 

 regularly arranged chlorophyll vesicles. In the earliest 

 stage of formation of the cell, before the commencement 

 of the circulating motion, the mucilaginous contents, 

 surrounding a nucleus, fill up the whole cavity of the 

 cell. The flowing movement, which carries along with it 

 the nucleus still visible for some time, first commences 

 after a hollow space filled with water has been formed in 

 the cell; but the separate formation of the primordial 

 membrane taking no share in this motion, must have 

 been completed before the commencement of the circu- 

 lation. In QSdoffonium, in the contraction of the contents 

 connected with the death of the cell, we frequently see 

 the mucilaginous layer divide into a double utricle, an 

 outer, lighter coloured, and an inner, darker coloured, 

 and never contracted. The compound nature of the 

 mucilaginous layer of (Edoffonium may be detected even 

 in the living cell, by the different arrangement of the 

 chlorophyll in the two layers. In the outer layer the 

 chlorophyll forms delicate longitudinal streaks, anasto- 

 mosing here and there, and thus forming a network with 

 narrow meshes ; the chlorophyll vesicles, which are ulti- 

 mately arranged in rows, are formed in these originally 

 amorphous streaks. Inside this light-green, long-streaked 

 net, we see, especially clearly in (E. fonticola and OH. 

 capillare, a coarser, darker green net, forming a few 

 irregular meshes, extending more in a cross direction, in 

 which net are imbedded large starch vesicles (in the 

 former species one or two, in the latter a greater number). 

 In this inner layer is found also the parietal nucleus, 

 remaining visible for a very long time. I'inally, in 



