180 UTRICULAR STRUCTURES. 



(or section), but also in the acquirement of a different 

 shape, as seen in front. Here also the utricles at first 

 appear round. They either remain round or become 

 elliptical. If they lie close together, they become paren- 

 chymatous (fig. 11, fig. 13). If colour-utricles increase 

 in length, this takes place either parallel to the long axis 

 of the 'cell, or if they lie in a circulation thread, in the 

 direction of the current. I have observed the latter in 

 the Algae (e. g. in Conferva glomerata marina). On the 

 inner surface of the cell-wall lies a network of muci- 

 laginous filaments. The chlorophyll-utricles form simple 

 rows in the lines of the reticulation (fig. 16). They extend 

 in length in the direction of the lines, and may become 

 lanceolate, or even linear. Those lying in the angles of 

 the network assume a triangular form; the angles are 

 more or less drawn out in the direction of the filaments 

 of circulation towards which they are turned. In Floridese 

 (e. g. in Ceramium diaphanum) I saw the red utricles, which 

 were originally round, elongate so much in the direction 

 of the longitudinal diameter of the cell, that they had the 

 appearance of long fibres. In this case their transverse 

 diameter diminished considerably. 



The growth of the colour-utricles presents great simi- 

 larity to the universal growth of cells. It exhibits on the 

 one side the transition from the globular to the tabular 

 form, on the other from the globular to the elongated, 

 fusiform or filamentous shape. They may also become 

 elongated into separate processes, almost like stellate cells. 

 Moreover, by pressure they may become parenchymatous. 



The expansion which is connected with the growth of 

 the colour-utricles exhibits great quantitative differences. 

 It is greatest in those which originate free in the cell-con- 

 tents, since they appear first as very minute granules. It 

 is less in those which have been produced by the division 

 of a parent-utricle ; here it amounts, as a rule, to two to 

 three times the original length and breadth ; otherwise the 

 growth is not always connected with an increase of size 

 in all diameters ; in tabular and very much flattened 



