36 



The cells of Characeae are filled with protoplasm; the nucleus of 

 the cells which form the nodes does not divide after the structure 

 of the plant is fully developed, but in the long internodal cells the 

 nucleus becomes divided into a number of fragmentary neuclei. In 

 the protoplasm various substances develop, but early in the cell 

 life vacuoles form; these after a time come together, and result in 

 one large vacuole, which occupies the centre of the cell, while the 

 protoplasm lies about the sides. 



This protoplasm now circulates always in the direction of the 

 long axis of the cell, and carries with it the various granules im- 

 bedded or floating in it. In some parts this protoplasm is quite 

 thick; in others (toward the central parts of the cell) very thin and 

 watery. 



The chlorophyll grains adhere, mostly, to the walls of the cells 

 and form a green layer of granules, arranged in beaded lines, follow- 

 ing the direction of the stream ; only in the line between the two 

 opposite streams is there a clear streak (the "indifferent line"), 

 which always marks the direction of the current. 



One can see in this circulating protoplasm curious granules of 

 protoplasm which are ciliated. 



The current is most rapid along the cell wall. Braun, in his 

 treatise referred to, states that no circulation has been observed in 

 the following parts of Charads : (i) in young fissating cells; for ex- 

 ample, in the growing apical cell and those lying next it ; (2) in cells 

 which abort early, as in the centre of the nodes of the stem and 

 leaves ; (3) in cells filled with starch and fat, as in the bulbils of 

 various species and in the spore cell ; (4) in the cells of the threads 

 which carry the spermatozoids ; (5) in the cells of the scuta of the 

 Antheridia. Al. Braun, in his work of over seventy-five pages, has 

 studied in detail the circulation in every part of a Charad; it is, how- 

 ever, unnecessary for us to quote farther from his work, or continue 

 the subject. 



CLASSIFICATION. As stated in the beginning of this treatise, the 

 position of the Characeae in the vegetable kingdom was long a matter 

 of doubt, and great diversity of opinion prevailed among early bot- 

 anists, and affected even Linnaeus. This uncertainty was eminently 

 true concerning the species. Scarcely any attempt to classify the 

 species was made. Vaellant, in 1719, described nine species, but 

 Linnaeus adopted but four (these four comprising several distinct 

 species, under one name, have been unwisely retained by later, 



