77 



Fam. V. CHARACE.E. 



Char. Stem dichotomoiis and jointed ; each joint composed 

 either as in Nitella of a single cell or tube, or as in Chara 

 of a single cell surrounded hy other smaller contiguous cells, 

 lohich take a spiral direction ; each articulation more- 

 over is surmounted hy a variable number of branches three 

 or four times jointed, ivhich are arranged in the form 

 of a verticillum or whorl, and at the joints of which the 

 reproductive organs are situated : these are of two hinds, 

 consisting of nucules and globules. Circulation spiral, and 

 distinct in each cell. 



Following the example of those more recent Algologists 

 who consider the Characece as AlgcB, I give this order a pro- 

 minent place amongst the British freshwater Algce, a position 

 to which they are well entitled, both on the ground of their 

 greater comparative complexity of structure, and of the high 

 interest attached to certain phenomena connected with their 

 history. 



The phenomena more particularly alluded to in the pre- 

 ceding paragraph are twofold ; the first having reference 

 to the circulation in the cells of which the different spe- 

 cies of this order are composed, and the second to the ex- 

 istence of spermatozoa in the globules or male blossoms. 

 These phenomena are confined amongst the freshwater di- 

 vision of the AlgcB to the Characecs. 



In order that the nature of the circulation (which will first 

 be considered), carried on in the cells of the Characece, may be 

 more clearly understood, it will be advisable, previously to 

 entering upon its consideration, to give a general notion of 

 the structure of these curious productions. 



The order Characece is divided into two genera, Chara 

 and Nitella. The main stems of the different species of 



