48 Halicystis and Valonia. 



with cell-sap. The small, green chromatophores (plate xill., figs. 2 & 3) 

 lie almost everywhere in a single more or less dense layer in the proto- 

 plasmic coat. At the upper arched portion of the bladder this layer 

 becomes very dense, and in places so much so, that the granules no 

 longer lie flat, but become partly tilted over on each other. Below this 

 the press of granules is less, and on the sides where they lie flat, spaces 

 appear free from granules. The chlorophyll-grains themselves are small, 

 flat roundish or oval disks of somewhat varying size and rounded outline, 

 and I have never seen sharply angular or lobed forms. These disks are 

 wholly without pyrenoids, and I could not discover in the minutely 

 examined specimen of this Alga any amylum in the whole protoplasmic 

 layer, rich in chromatophores as it is. 



Very numerous minute nuclei are distributed among the chromato- 

 phores, or lie on the inner surface of the chromatophore layer. They are 

 flattened disks, round or oval in outline, and contain each a minute 

 nucleolus. The nuclei are to be detected only here and there in specimens 

 hardened without staining ; but after this process they may be easily 

 recognised. Without staining, the minute glistening nucleoli may be 

 recognised in the spaces free from chlorophyll-grains. The nuclei are 

 scattered irregularly throughout the whole protoplasmic layer, now singly, 

 now in pairs, or in groups of several near each other. In the living 

 plant they probably wander in the protoplasmic layer, as for example 

 those of Codimn* do.' 



Dr. Schmitz then proceeds to point out the characters which distin- 

 guish Halicystis from Valonia, to some species of which it bears, as will be 

 seen later, a very striking resemblance. The nuclei of Valonia, as he has 

 pointed out.t are much more compact and more evenly distributed at 

 fairly regular distances in the protoplasm. The chromatophores exhibit an 

 irregularity of shape, being roundish, but angular, some of them with 

 sharp angles, and of varying size ; moreover, some of them are provided 

 with pyrenoids, and these are of regular occurrence among the others, 

 which have no pyrenoids. He comes to the conclusion that the above 

 differences of characters in combination with the non-development of 

 rhizoids and a cell-membrane so little stratified as to exhibit no exfoliation 

 completely justify the separation of Halicystis from Valonia, as Areschoug 

 has done. Dr. Schmitz goes further, and insists on the removal of the 



* Berthold, Zur Kenntniss der SipJwneen imd Bangiaceen (Mittheil. d. Zoolog. Station 

 A'capel, ii., p. 76). 



+ Beobachtungen iiber die vielkernigen Zellen dcr Siphonocladiaceen. Halle, 1879. 

 \ Phyc. Scandinav., p. 446. Upsala, 1850. 



