94 Dr. R. Caspary on Furcellaria fastigiata 



as I bave done with Furcellaria fastigiata. Fig. 28. PI. VI. re- 

 presents some of these cells in a transverse section. 



The inner part of the epidermal stratum of cells, b, fig. 8 & 9, 

 is in every respect like that of Furcellaria fastigiata, with this 

 exception, that the walls of the cells never exhibit a greenish, but 

 a brownish tinge. 



The second sort of cells in Polyides rotundus, B, fig. 8 & 9, is 

 entirely like the corresponding cells in Furcellaria fasiigiattty 

 fig. 1 &2B. Their absolute size was,00347"'; 0-0280"'; O-OSIS'"; 

 0-0304'" ; 0-0257"' ; 00235'" par. 



The second sort of cells is transformed, by their being placed 

 in strings, by growing in length and taking a slanting direction 

 to the axis of the stem, into the third sort. In fig, 8 & 9 C these 

 cells are represented running between the long perpendicular 

 cells, but neither as horizontally as in Fwrcellaria fastigiata, nor 

 in all directions as there, but slanting to the axis of the stem 

 and less deviating from a straight line. They are also propor- 

 tionally of a greater thickness than those of F. fastigiata. The 

 walls of these cells are simple, transparent, colourless, their con- 

 tents constantly globose, pellucid, colourless grains, which iodine 

 colours just as brown, if seen in mass, or dirty violet, if seen sin- 

 gle, as the grains of the second sort. The absolute measure in 

 five was the following : 0-0510"' ; 0-0167'"; 0-0160'"; 0-0452'"; 

 0-0482'" par. 



I am disposed to think that these cells of the third sort change 

 by degrees into the cells of the fourth sort, but I have never 

 been able to ascertain this by direct observation. The cells of 

 the fourth sort are in the middle of the stem, fig. 8 & 9 D, run- 

 ning parallel to each other and the axis of the stem, being con- 

 nected with each other at the ends ; the relative proportion of 

 their breadth : length =1 : 8—15. They are not entirely cylin- 

 drical, but mostly much thicker at the ends than in the middle, 

 so that they have the form of a femur. Fig. 11 & 16 show the 

 greater thickness of the ends of these cells and the meeting of 

 two. The wall colourless and transparent ; the contents whitish, 

 not well-defined grains, running one into another. I was never 

 able to perceive clearly in the longitudinal section a double layer 

 in the wall. Fig. 1 1 represents one of the cells having a triple 

 outline on the outside, and one would therefore suppose that 

 the wall consists of two layers, but the innermost two lines do 

 not seem to indicate an inner layer of the wall, but a deposit 

 of the granular contents of the cell along it. The transverse 

 section however shows the double layers of the walls in the cells 

 very clearly, just as in Furcellaria fastigiata : see fig. 14 & 15. The 

 absolute measure of seventeen of these cells is, 00750'"; 00947"'; 



