358 Frof, Nordenslndld — Exj^edition to Greenland. 



contour, in tlie extremity of whicli two kernel-formed rounded 

 bodies are imbedded, which in general cannot be perceived by 

 the eyQ till the colouring-matter has been removed by means of 

 reagents. We sometimes meet with four such bodies in one cell, 

 sometimes but a single one : the former a result of accidentally 

 checked division of the cells ; the latter of such division having lately 

 taken place. In the liquid of the cells a number of small grains are 

 found, which are for the most part collected round the periphery of 

 the cell or at its ends. 



" Judging from the construction of the cells, and the manner of 

 their multiplication, the alga before us would appear to belong to 

 the Gonjugatce ; but as I have not succeeded in discovering fructifica- 

 tion in it, it would be rash to decide to which genus it is to be 

 referred. Tlie thread-like rows of connected cells agree with 

 the Zygnemaceos ; whereas, on the other hand, an unmistakable 

 similitude to the Besmidiacece, especially Vylindrocystis, and the 

 nearly related genera, is indicated by the strongly-marked divisions 

 into multiples of two, and by the tendency of the rows of cells 

 to fall asunder, as far as the destructibility of the uniting cell- 

 membranes permits, into parts consisting of cells united in pairs, which 

 however is seldom possible, in consequence of the greater energy 

 possessed by the power of multiplying the cells. As the above- 

 mentioned small single cells, which occur in great numbers, are 

 much less in diameter than those cells which arise from the bisection 

 of the threads, they have perhaps a different origin from these latter, 

 although the researches which I have hitherto been enabled to devote 

 to this subject have not furnished any illustration of it. "Were 

 these daughter-cells arising from the division of the sporas, if the 

 above-mentioned supposition with respect to the systematic place of 

 the species be correct, the stadium of copulation or sporee, in some 

 period of its development, ought to be found. Two rare forms of 

 peculiarly constructed cells perhaps ought not to be passed over in 

 silence. I have sometimes found the extreme cell in a thread con- 

 siderably more swelled than the others, more elliptic in form, also 

 provided with a thicker membrane, and with the contents of the cell 

 more coarse-grained. I once found one of the middle cells in a 

 thread thus transformed, and on two occasions I have met with 

 single cells of the same kind. I also once met with a cell 

 of very peculiar construction. It had the usual form, but was un- 

 usually large, with a long mass of chlorophyll, as usual, in the midst, 

 and the granular matter grouped rather towards the ends of the cell. 

 In it were found about twenty larger or smaller spherical bodies. 

 Four of these lay arranged at each end of the cell, and were almost 

 entirely opaque, of a dark brown colour, and in appearance much 

 resembled the smaller cells of Protococcus nivalis. The others were 

 translucent, with sharply defined contours. As our knowledge of 

 the nature of these bodies is confined to what is here stated, the 

 fuller explanation of their significance must be reserved for a future 

 investigation. 



" In places similar to those in which this species occurs, and often 



