





IN VEGETABLE BIOLOGY. 



509 







































A Short Account op Ballia callitricha, Ag* 



Ihe thallus oi Ballia callitricha consists of a main axis com- 

 posed of a single series of cells, each of which bears on either 





side a 



axis, of which the basal cell is formed 





upper end of the parent-cell : these secondary branches lie in two 

 series, the individual members of both series lying in the same 

 plane as their predecessors. Each secondary branch, in its turn, 

 branches in the same way as its parent ; and so with branches of 



late 

 th 



ramifications 













6 plant therefore consists of a series of systems of superposed 

 binary verticils all with their median plane coinciding. This 

 arrangement is afterwards complicated by cortication of the axis, 



which commences by downward growth of the basal cell of each 

 branch. 



The septa between contiguous cells of the same order of rami- 

 fication are saddle-shaped, the side of the saddle being visible in 

 the ordinary view. This accounts for the peculiar appearance of 

 each septum, from which one might conclude that the upper cell 

 intrudes upon the lower, whereas, as Archer f first showed, pre- 

 cisely the reverse is the case. The saddle is shown in Plate XIV. 

 %• 4; in the other figures it has been thought sufficient to draw 

 its upper part alone. 



Atthi 



Jrn 







own since the date of Archer's paper as " stoppers " : these 

 are highly refractive as seen in dried specimens moistened, and 

 more or less hemispherical in shape with a flat base by which 

 each is applied to a sort of bed of cell-wall. There is, however, no 

 adhesion between stopper aud wall, for the former can easily be 

 detached from the latter, under which circumstances, if the means 

 taken to separate them have not been too violent, the stopper 

 may be seen to be hanging by plasmatic threads to the bed. By 



appropriate means (S 



solution, xanthoproteic test, 



Millon's reagent, hydric sulphate, Schulze's macerating fluid) 

 a single plasma-bridge or several threads of plasma can be seen 

 runniug from stopper to stopper ; these threads do not appear to 

 traverse the stopper itself but to run out to its edge, and by thjs 

 weans neighbouring protoplasts are put in communication. 







Vide Archer in Trans. Linn. Soc., 2nd series, Bot. vol. i. 



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