Dr. R. Caspary on tlie Hairs of marine Algce. 471 



0-0195'". The interior of the cavity of the couceptacle shows 

 amongst the antheridia and spores forked or simple hairs, con- 

 sisting of a few short, thick cells, having a nucleus, formed by a 

 heap of slime, attached to the wall, along which it sends out 

 some threads of slime, which although visible without iodine, 

 appear better if coloured brown by it. Fig. 20 and 22 represent 

 such hairs with their nucleus attached to the wall, and its slime- 

 threads. I observe, that not only these hairs have the nucleus 

 attached to the wall, but also the cells of the interior of the 

 stem of Cystoseira granulata and ericoides. Nageli (Memoir on 

 the Nuclei, &c., translated by Arthur Henfrey, published by the 

 Eay Society, 1846, p. 223) is mistaken in stating that the nucleu.s 

 in the genus Cystoseira is a free and central one; I found it in 

 Cystoseira granulata and ericoides to be attached to the wall. 



Rhodomela subfusca, Polysiphonia urceolata, fibrillosa and ni- 

 grescens have dichotomously divided hairs ; those of Rhodomela 

 subfusca, Polysiphonia urceolata and fibrillosa are twice, those 

 of Polysiphonia nigrescens four to five times dichotomous. The 

 basal cells are the thickest, those towards the point attenuated. 

 Such hairs form tufts on the points of the branches. Harvey, 

 * Manual/ p. 71, observes : " They will be found in every species 

 (of Polysiphonia), if the specimen examined be in a sufficient 

 young state.'' The presence of the hairs is however not dependent 

 upon the young state of the specimens — even decaying ones of the 

 above-named species of Polysiphonia exhibited them — but upon 

 their place of growth, whether this was an exposed one or not. I 

 add, that I have n'ot observed such hairs on Polysiphonia fastigiata, 

 many as have been the specimens which I have examined; but 

 I have not seen specimens from deep water. As the dichotomous 

 hairs of the above-named four plants are entirely alike, with the 

 exception of the one difference already stated, to describe one 

 will be to describe all. Fig. 21 represents a mature hair of Poly- 

 siphonia urceolata; it has no visible contents. PI. XVII. fig. 17. 

 represents a point of a branch of Polysiphonia urceolata : A is the 

 point of the branch, B is a hair in its first stage of growth. It 

 is already dichotomously divided in the two branches c and d, 

 which, as the base of the hair does, show already the division - 

 walls of their cells ; but those of the base are very obscure, and 

 only recognizable in the middle. The contents are a slimy, 

 granular, brownish mass, which by contmued gi'owth is dis- 

 coloured and remains only in the middle of the cell, attached to 

 its wall. The two branches c and d bear each on one cell a 

 protuberance e and/, not yet separated by a partition-wall from 

 their mother-cell. These protuberances are the first beginnings 

 of the second dichotomous division. Fig. 19 represents a point 

 of another hair, in which the cells are as yet entirely filled with 



