AKCnEE, — ON PALM0GLO3A MACROCOCCA (kUTZ.). 31 



Locality. — Between Loughs Luggelaw (or Tay) and Dan, near Bal- 

 linrush. 



General Description. — Mass pale yellowish-green, gelatinous ; cells 

 broadly elliptic, chlorophyll-plate in edge view very narrow, excentric, 

 not rapidly attenuated to the extremities, which are not acute, and do 

 not quite touch the cell-wall, often curved ; endochrome dense. 



I have observed the cell-contents bounded by the " primordial utri- 

 cle" escape from the parent- cell without conjugation, through a lateral 

 or terminal or intermediately disposed opening, effected by the raising 

 up and often separation of a lid or valve-like portion of the parent- 

 cell membrane (PL I., Pigs. 22 to 31). During tbis operation the contents 

 are often much constricted, by reason of the narrow orifice through 

 which the mass makes an exit. After emergence it becomes rounded, 

 and the contents of this resting-spore-like body (Figs. 24, 25), which do 

 not conjugate or combine with any other, become of a reddish-brown 

 hue, with a dark corpuscle in the centre. The empty parent-cell mem- 

 brane lies hard by, the lid-like structure sometimes apparently still 

 adherent by one point — sometimes wholly detached, and lying about in 

 various positions, or lost altogether (Pigs. 22 to 31). 



What may be the fate of these resting-spore-like bodies I cannot 

 say ; but to my mind they form an additional reason for dissenting from 

 Hicks's conclusion, already referred to, that " Palmoglcea forms" are 

 any condition of developing gonidia of Lichens. Somewhat similar 

 spore- like bodies are sometimes formed in Zygnema — one such from the 

 entire cell-contents of one cell — and they escape from the parent-cell 

 through a lateral opening into the surrounding water ; but I have not 

 observed in Zygnema that the opening by which they escape is produced 

 by their raising up of a portion of the cell-membrane as a lid or valve- 

 like structure, which forms so remarkable a feature in this Mesotscnium. 

 Similar " resting cells," not resulting from conjugation, are described 

 by De Bary in a Zygnema,* distinguishable from the "spores'' by their 

 more cylindrical figure, and which germinate into young plants. But 

 in this Mesotaenium this "lid" does not form a specially formed cap 

 (so to speak) like that, for instance, in some species of Chytridium, 

 (Braun) there for the exit of zoospores, but seems to be merely a small 

 portion of the cell-membrane pushed up from within at any point. This 

 "lid," however, is of a somewhat sharply defined outline, and of a 

 rounded figure, as it were cut out, and not produced by a rough burst- 

 ing or tearing ; and yet there can be no suture, the line of separation 

 taking place in the most varied directions and positions, between trans- 

 verse, oblique, and vertical. It is well known that somewhat similar 

 spore-like bodies are formed by the individualization of the whole or a 

 portion of the cell-contents in some Desmids, in Spirogyra (here beset 

 with spine-like extensions), &c, but they do not seem to have been 

 noticed as yet as being eventually set free ; and if they arc so, it must 



Op. cit.," p. 10, t. viii., 13. 



