PALMELLACE.E. 23 



plant agreed with Reinsch's in the dimensions of the cells, their oval 

 figure (truncate after division, whilst closely apposecl, and until full size 

 is again attained), their longer diameter posed in the direction of the 

 length of the cylindrical filament and in their being involved by a 

 number of concentric hyaline investments standing off from the cells at 

 the poles, closely applied at the sides ; not, however (as Reinsch shows) 

 uniformly four, but two, three, or four, and standing off from the cells, 

 not equidistantly, but at different distances. It is, however, quite 

 possible that where the fewer number only of laminae of the envelopes 

 were apparent, others may have been present, but so closely applied to 

 the cells (and to each other) as to appear as if absent. Just as depicted 

 by Reinsch (though his figure be rather stiff), I saw some of the cells 

 undergoing self-division, the fission always taking place through the 

 shorter diameter, the new cells, at first flattened at the ends, then grow- 

 ing as long as the older, and becoming rounded off, and thus the longi- 

 tudinal direction of the cells is maintained. Thus this form is unlike 

 Cylindrocapsa nuda (Reinsch), in which the oval cells are placed trans- 

 versely, and appear to be without the loose outer envelopes. The 

 author does not state that the contents are not a bright, but a dull lurid 

 green, very opaque. On endeavouring to preserve this plant, it ' kept ' 

 not at all, colour became lost, envelope shrivelled, and even after a 

 couple of days the examples did not represent the same thing as when 

 fresh. 



" Thus the morphology of the plant points to an affinity with Hormo- 

 spora, Breb., which, too, has its forms with the elliptic cells placed 

 longitudinally (If. mutabilis and others) and transversely (H. transver- 

 salis), but no Hormospora, except H ramosa, Thwaites, appears 

 attached; the contents, too, are bright green, and seem to show a 

 characteristic internal arrangement not seen in Cylindrocapsa ; the 

 outer investment is also more mucous. As a form, or a form-species, 

 (for, doubtless, such as those belonging to Cylindrocapsa and Hormo- 

 spora can all be accounted no more, so long as no reproductive process 

 is known) the present plant (Cylindrocapsa involuta} is, per se, abun- 

 dantly distinct. It appears to be very rare, so does C. nuda, 

 which I only once met with ; neither is recorded by Rabenhorst in 

 Tlor. Europ.' 



" But whether these Cylindrocapsa-forms be mere stages of other 

 growths mere form-species or permanent parthenogenetic species 

 they are entitled to hold a place for purposes of reference until happily 

 more be, if ever, known as to their development and their right to 

 rank as independent plants.'' Grev. III. 40. 



Plate IX. f,g. 3. Portions showing spores X 400 diam. 



Cylindrocapsa nuda. Reinsch Alg. p. 67, t. 6, /. 2. 



Undivided cells ellipsoid, membrane thick, without teguments, 

 filaments now and then thickened and enclosing four cells. 

 SIZE. Tube -023--03 mm. diam. 



In streams. Ireland. 



Cienkowski's* researches on Cylindrocapsa involuta achieved such im- 

 portant results that they must be indicated here, since the reproduction 

 will, doubtless, be identical in both species. 



" This alga possesses antheridia and oogonia. The oogonium is a 

 globular inflated joint, it consists of contents and wall; the first presents 



* Cienkowski, " Zur Morphologic der Ulotricheen," in Melanges Acad. 

 Imp. de St. Petersburg, t. ix. p. 531. 



