UTRICULAR STRUCTURES. 179 



in the second cell, 150; in the third, 500; and in the 

 fourth, and longest cell, 2000. During the growth of 

 the cell from a length = *080 of a line to 6 lines, the 

 number of chlorophyll-utricles had increased in each row 

 from 40 to 2000, and in the whole cell from 3200 to 

 160,000. Consequently, while the cell became seventy- 

 five times longer, the chorophyll-utricles increased* about 

 fiftyfold. 



I found the like in the cells of the stem of the same 

 plant. In a length of 1*3, and a diameter of '14 of a 

 line, I counted about 160 rows, in each row about 325 

 utricles ; in one about 20 lines long and *2 in diameter, 

 again about 160 rows, but some 3500 utricles in each 

 row ; and lastly, in a cell 30 lines long, and of a diameter 

 = '24, I found about 160 rows, and some 6700 chlo- 

 rophyll-utricles in each row. Here also the utricles 

 were of tolerably equal size, and in regular arrangement 

 in the cell. Individuals exhibited transverse division ; 

 but I saw no young, minute utricles between the others, 

 so that here also the increase in number could only be 

 effected by division. This increase amounted to about 

 twenty times the number, while the cell increased about 

 twenty-three times in length. 



If the colour-utricles originate free in the cell-contents, 

 their shape is at first globular ; if they are produced by 

 the division of a parent-utricle, at first hemispherical or 

 semi-ellipsoidal. In the latter case they soon assume a 

 globular form as they separate from each other. If the 

 utricles, as rarely happens, remain free, so that they swim 

 in the cell-contents, they retain their globular form. 

 Usually they apply themselves upon the wall, whereby 

 their form is more or less altered, since they become more 

 or less flattened. Their section is then either almost 

 round, oval, hemispherical, serai-elliptical, or flatly com- 

 pressed. 



The alteration of form which the colour-utricles undergo 

 during their growth consists not only of a mere flattening 

 of greater or less extent, which we see in the side view 



