l)r. R. Caspary on a neiv British Alya. 267 



as long as one neighbouring, not yet divided cell. The cells of 

 the apex are often longer than those in the middle and much 

 thinner ; their length is 0-0028"' ; 0-0038'". Fig. 4 represents 

 the point of a branch, 1300 times magnified. The cells are often 

 scarcely distinguishable, particularly in the under part of the stem. 

 The contents of the cells are light green, fine grains, coloured by 

 iodine dark brown, but not afi'ected by muriatic acid and spirits 

 of wine. In the middle of the cell is often one larger, appa- 

 rently colourless globule (see fig. 8), breaking the light stronger 

 than the surrounding contents of the cell. I could not observe 

 that this globule had any connection with the formation of the 

 cells. The hair-like apices contain, besides a colourless fluid, 

 only a few granules of chlorophyll. The undermost cell of each 

 branch is hemispherical, broader than the other cells of the 

 branch, has a very visible wall, which I never saw in the other 

 cells, and mostly, as in fig. 6 a, a little hemispherical elevation on 

 the inner side of the upper wall, as if this was a nucleus attached 

 to the wall. The contents consist of a light brownish, trans- 

 parent fluid, without grains. But the most peculiar circumstance 

 is, that the undermost cell of the branch does not cohere with 

 the cells of the stem, being considerably removed from it to one 

 side, as shown in fig. 6. The branch is only connected with the 

 stem by a sheath of slime, enveloping both. The cells in the 

 main stem, or those immediately over the basal cell of a branch, 

 frequently acquire somewhat the character of the basal cell. 

 Fig. 1 and 3 represent such cells. They are more or less cylin- 

 drical, often very much prolonged, elliptical, or the dimension of 

 their breadth is by far greater than that of their length, and the 

 granular contents have disappeared, the cells representing one 

 brownish, semitransparent mass, of which I cannot say if it is 

 sohd or not. The walls between such cells are very visible, or 

 are rather not distinguishable from the substance of the sheath. 

 The length of some of these cells was 0-0019'" ; 0-0039'". 



The stem and the branches are, with the exception of the apices, 

 enveloped in a sheath of brownish green jelly. This sheath is 

 composed of many funnel-shaped gelatine tubes, succeeding each 

 other at little distances ; the upper part with its thinner end in 

 the wider of the lower, and surrounding the stem in such a way 

 that this seems almost to be covered with a solid gelatinous mass. 

 The upper margin of each tube is split in a great many hair-like 

 threads of very minute diametei', which frequently curl about in 

 an irregular manner, but often represent a phjenomenon very 

 rarely found amongst Algre, that they form a real spiral round 

 the gelatinous cover of one or two branches or stems. 



Fig. 7 represents a part of the base of a stem ; in the middle 



18* 



