of Sphaeroplea annulina. 87 



the fine capillary parts of the elongating ends may always be 

 observed, — a fact hitherto overlooked. 



The contents of the full-grown cells of Sphcsroplea exhibit 

 most elegant structures, the comprehension of which is essentially 

 furthered by the interesting investigations of Al. Braun. The 

 constituents, colourless protoplasm, green chlorophyll, aqueous 

 fluid and starch-granules, are distributed in a peculiar manner, 

 the aqueous fluid forming large bubbles or vacuoles which attain 

 a diameter almost equal to that of the cell, and hence stand in 

 rows, like pearls, often in contact at their poles, and flattened 

 there so as to form seeming septa. In the interval between the 

 vacuoles is compressed the green plasma with the starch-gra- 

 nules ; and here further the space becomes disputed by nume- 

 rous smaller vacuoles which are excreted from the plasma : under 

 a low magnifying power the whole appears as if there was a 

 regular alternation of narrow green and broad colourless rings. 

 If the vacuoles are smaller and the chlorophyll is more abun- 

 dant, the cell appears uniformly green, — more intense merely in 

 the interval between the vacuoles. The vacuoles have an enve- 

 lope of condensed plasma, so that when the whole is softened in 

 water the vacuoles do not dissolve, but sustain themselves for a 

 long time, like cells ; but they are not permanent structures ; 

 their number and size are subject to constant alteration. 



In the second half of April I first observed the germinated fila- 

 ments of Sphseroplea beginning to reproduce spores. The regular 

 arrangement of the green rings disappeared in particular cells ; 

 the vacuoles increased in number, so that the w^hole contents 

 assumed the appearance of a green froth ; the starch-globules 

 were irregularly diff'used through this. These were soon seen 

 to become grouped together in twos or threes, and largish 

 masses of the green plasma became accumulated around them ; 

 after a certain time the middle line of the cell was occupied by a 

 great number of green lumps, at regular distances, the frothy 

 matter being distributed between them. As the majority of the 

 vacuoles gradually disappeared these lumps assumed the form of 

 green stars, such as occur in pairs in the cells of Zygnema, re- 

 maining connected together by the green radiating filaments of 

 plasma. Between each pair of these stellate masses a large 

 vacuole was formed, which became flattened to level septa, so 

 that the whole cell appeared as if divided into chambers by a 

 number of parallel plates of plasma. In each of these chambers 

 there began an uninterrupted metamorphosis of the green mass ; 

 the mucilaginous filaments were gradually retracted ; the green 

 substance contracted itself sometimes towards the right, some- 

 times to the left ; in a short time the colourless })lasma had 

 become so distributed around the chlorophyll that the septa of 



