468 Dr. R. Caspary on the Hairs of marine Alga. 



more numerous on not quite young parts of the branches, than 

 on the apices, Ph XV. fig. 1 represents a point of a branch of Cer. 

 ciliatum, which shows as yet only spines on the back, and three 

 hairs between them, here and there dotted with portions of shme. 

 Fig. 3 exhibits such a hair of Cer. ruhrum, and fig. 24, PI. XVII. a 

 point of a branch of Cer. ruhrum, seen with a moderate power. The 

 length of the hairs isiO-lSGo"'; 0-1566'"; 01272'". Iodine 

 colours the contents dark brown, but not the membrane. Dif- 

 ferent and not to be confounded with these hairs, are little 

 threads of fixation, sent out at the nodes at the basis of the stem, 

 consisting of a single row of cells without granular contents, here 

 and there branched. Fig. 2 represents such threads of fixation 

 produced by one of the nodes at the base of a specimen of Cer. 

 ciliatum. 1 saw these threads of fixation also on Cer. acantho- 

 notum. 



In Sphacetaria cirrhosa, a single hair is formed near the point 

 of the branches on the upper part of one of the cells ; it is un- 

 divided, but consists of about nine or ten cells and is closely 

 appressed to the branch. The length of the single cells in these 

 hairs is : 0-1534"' ; 0-0886"' ; 00686'" ; 00339'" ; 0-0261'". It 

 is very interesting to see it in its different stages of growth. 

 The topmost cell of a young branch forms several protuberances, 

 two or three thick and rounded, but one thin and pointed. 

 Fig. 6 represents a point of a branch with three protuberances. 

 The highest and thickest, c, becomes the continuation of the 

 axis of the stem ; c, a side branch, and b, a hair. None of these 

 protuberances are as yet separated by a partition-wall from the 

 cell which produced them. But this partition-wall is finally 

 formed, the hair lengthens now and is quite full of grayish or 

 brownish granular contents. Then at the point of it begins 

 first to appear a division-wall or several, as in fig. 5, where 

 the interior of the young hair exhibits at the point three division- 

 walls, but the whole of each of these divisions is still filled with 

 granular contents. These separate finally from the division- 

 walls and become the centre of the growth of the cell, sending 

 out threads of slime to and along the wall of it, as seen in fig. 4, 

 in the fifth and fourth cell from the point ; then by degrees the 

 cell lengthens more and more, the threads of slime disappear, 

 and in the middle of the cell alone is found a small heap of 

 grains, of which I had no opportunity of deciding if it is attached 

 to the wall or free. Fig. 4 represents an almost mature hair, 

 showing all the stages of the growth of the cells. The single, 

 lateral, appressed hair in Sphacetaria cirrhosa affords a good 

 specific character. 



In Chorda filum and lomentaria, and in Punctaria plantaginea, 

 are scattered over the whole frond tufts of hairs, having about 



