and Polyides rotundus. 9S 



degrees worn away and washed off, as remains of the sporangia 

 still fixed to the stem entirely robbed of their epidermal coat are 

 often met with ; it seems therefore not accurate to say that " the 

 receptacles fall off when ripe," particularly as they have no arti- 

 culation ; nevertheless it would be desirable to make more obser- 

 vations on this point. 



The power of reproduction is very great in Furcellaria fasti- 

 giata as well as in Polyides rotundus. Stems are often found, 

 which have been by accident cut off on the upper branches once, 

 twice, or even three times, and so truncated, but which have 

 always protruded again a new grown stem beyond the truncated 

 parts. I figure one piece in which truncation has taken place 

 three times (PI. V. fig. 10). 



Fig. 9 represents a transverse section of the stem of Polyides 

 rotundus, and fig. 8 a longitudinal one. There are also four sorts 

 of cells in the stem of Polyides rotundus : — 



1st. The epidermal cells A, fig. 8 & 9. The walls colourless 

 or with a sHght brownish tinge ; intercellular spaces filled up 

 with a transparent colourless matter, probably slime. Contents 

 brown grains, not free, but attached to the walls. This stratum 

 of epidermal cells consists of two subdivisions. The outer part 

 of the stratum, a, fig. 8 & 9, formed by small cells, placed in ra- 

 diating rows ; the breadth of these cells is almost equal to their 

 length ; the relative proportion of breadth : width : length = 1:1: 

 1-1|^, rarely to 3. Seen from above they exhibit themselves 

 4-7-sided, but the polygonals are so rounded on the comers that 

 they represent a great approach to cylinders ; four or five layers 

 of such cells are generally to be met with, occasionally only three, 

 but also six or more. Their absolute measure is the following : — 



Seen from above they represent as well as those of Furcellaria 

 fastigiata two circles, which are to be explained in the same way 



