1 1 2 LUBLIN UNIVERSITY 



smaller and more slender plant, and of a different outline (Fig. 6). This 

 form, too, occurs filamentous, but is very fragile. It differs from Doct- 

 dium asperum (Breb.) in each joint being fusiform, at the middle of 

 which, where it is broadest, it is little more than one-half the diameter 

 of that species, whence it gradually tapers towards the extremities, 

 which become somewhat suddenly dilated, giving to the ends a slightly 

 capitate appearance. It, too, is rough on the surface with minute scat- 

 tered granules. I think this form differs materially from the variety of 

 Docidium asperum figured in Half s after M. de Brebisson, which is quite 

 as large a plant both in the diameter and length of the cells as that spe- 

 cies, which are not at all fusiform, and differ only in the extremities 

 being somewhat constricted beneath the apex. I have found this fusi- 

 form species also to present a central division of the endochrome, which 

 is also of a contracted waved outline, enclosing a central series of cor- 

 puscles similarly to Doctdium asperum (Bre"b.), and to the first noticed 

 species. In this species I have also noticed indications of the same 

 mode of division as described and figured in the first form. There is 

 no perceptible gelatinous sheath, so far as I can make out, surrounding 

 any of these three organisms. I regret I have not been fortunate enough 

 to meet with the reproductive state of any of them. If I might ven- 

 ture on a conjecture, I should probably say that it takes place by con- 

 jugation of the separated joints. 



It will be by this time seen that the end at which I aim is to indi- 

 cate that I think the first-described organism, D. asperum (Breb.), and 

 the fusiform species, belong to the same genus. It is true I have not 

 been able to see moving granules at the extremities of Doctdium asperum 

 (Breb.) nor of the fusiform species, although, on the authority of Mr. 

 "Ralfs, it is stated that M. de Brebisson has seen them in the former. For 

 my part, I do not doubt that they may exist, for it seems to me that 

 the rather opaque asperities which cover the surface of the joints may 

 hinder them being noticed. I have sometimes thought I saw them, but 

 could never feel positive. In any case I might remark that we have 

 species of Penium both with and without active granules. 



Assuming it as granted that these three forms belong to the samo 

 genus, it may be thought necessary to inquire, is that genus Docidium ? 

 I do not think so. In the first place, all these species entirely want any 

 constriction at the centre of the joints, nor are the segments at all di- 

 lated at the base ; both which are, as it appears to me, essential cha- 



