CHARACE^. 



[ 162 ] 



CIIARACE^E. 



pavement, of chlorophyll-globules imbedded 

 in colourless protoplasm, arranged in a some- 

 what spiral order ; within them lies a thick 

 layer of semi gelatinous consistence (the 

 circulating protoplasm) ; and the centre is 

 filled up with a watery liquid. The circula- 

 tion in the ordinary cells consists in the 

 movement of the gelatinous protoplasmic 

 sac, as one mass, slowly up one side of the 

 cell, across the ends, and down the other 

 side, not perpendicularly, however, but in 

 an oblique or spiral course, as indicated in 

 fig. 125. The fluid in the centre does not 

 circulate, but contains vesicles, granules, or 

 other bodies floating in it, which are free, 

 and when resting upon the protoplasmic 

 sac, are carried along by it and up the side 

 of the cell, until they fall down again by 

 gravitation. The young cells from which 

 the fruits are developed exhibit a circula- 

 tion of green vesicles ; the cortical filaments 

 have acirculating primordial utricle without 

 chlorophyll- globules. 



The circulation is obscured in many Chares 

 by the existence of an incrustation of the 

 cell-wall by carbonate of lime, often found 

 in rhomboidal crystals. In C. (Nitella) 

 translucens, Jlexilis, and other species, this 

 does not exist ; and these species without 

 cortical tubes exhibit the phenomenon more 

 clearly than the others. Those species, 

 however, which are subject to incrustation 

 have comparatively little about the tips of 

 the shoots ; and if they are kept growing 

 for some time in a jar of water pretty free 

 from lime, new shoots maybe obtained very 

 suitable for examination. When we care- 

 fully examine the conical terminal cell of a 

 shoot, we find the following characters : 

 The cell-membrane is distinctly laminated, 

 and thickened at the conical apex of the 

 cell ; when sulphuric acid and iodine are 

 applied, the cell-wall exhibits a thick in- 

 ternal layer of a blue colour, indicating its 

 composition of cellulose, while a thin layer 

 extending all over the outside becomes 

 bright yellow, and thus presents a resem- 

 blance to the cuticular layer of the higher 

 plants. The cell-wall is lined by a thin 

 layer of protoplasm, in which are imbedded 

 a vast number of chlorophyll-globules, 

 closely set and arranged spirally, as above 

 stated ; a clear line extends obliquely up in 

 this layer, bare of chlorophyll. The chloro- 

 phyll-globules have much the appearance 

 of vesicles here, and contain starch- cor- 

 puscles, which cause the whole layer to 

 turn blue with iodine. (See CHLOBO- 



Fig. 121. 



Fig. 124. 



Fig. 121. A globule, magnified 50 diam., showing the 

 triangular valves. 



Fig. 122. A globule cut in half, to show the oblong 

 cells and the septate filaments in the centre, 50 diam. 



Fig. 123. Portion of a septate filament, 200 diam. ; 

 with two biciliated spermatozoids, 400 diam. 



Fig. 124. Chara translucens, showing its simple tubes 

 and nucules grouped in threes under the terminal 

 globule. 



Fig. 125. Diagram representing the course of the cir- 

 culation in the main tube and branches of Chara. 



PHYLL.) Within this motionless layer is 

 found the thick rotating layer of protoplasm, 

 in which again are imbedded numerous 

 starch and chlorophyll-globules, a vast num- 

 ber of minute granules, and a number of 

 globular bodies of larger size, 1-1500", ac- 

 cording to Goppert and Cohn covered with 

 rigid cilia. The internal boundary of this 



