Tort] LUTMAN—CLOSTERIUM 403 
FISCHER (15) in a later paper gave further details as to the 
origin in the new half of the end vacuoles and its crystals. He 
believed that the latter formed in the cytoplasm and later migrated 
into the vacuole. 
Some of FiscHER’s observations on the method in which the 
cell wall divides were criticized by both Gay (18) and Haupt- 
FLEISCH (23). Gavy’s paper I have not seen, but according to 
HAUPTELEISCH, who reviews it, he points out that FIsCHER’s 
results hold only for wall division in those varieties with thick walls 
on which were longitudinal and cross-markings. HAUPTFLEISCH 
showed further that in those forms without girdle rings, such as 
C. Ehrenbergii and C. moniliferum, the isolation of the daughter 
cells is accomplished by a simple splitting of the cross-wall. 
' Considerable work has been done by LiirKem@LLER (26) on 
the formation of the cell wall during the division process, but as 
little of his work has direct bearing on division in the species 
discussed in this paper, it will not be reviewed. Based on this work, 
LirKeMULieR has attempted to formulate a consistent scheme of 
phylogeny for the desmid group. He regards them as degenerate 
filamentous conjugates. This view he shares with West (46), 
who, as a result of studies on variation in desmids, had pub- 
lished an almost identical theory of their phylogeny three years 
previously. 
The very peculiar nucleus of the desmids was evidently a puzzle 
to the early observers. DEBAry (9) does not attempt to describe 
it, but Braun (5) has the following to say: ‘The nucleus, with its. 
colorless mucilaginous envelope, is maintained in the center of the 
spindle-shaped cell by the green lamellae of contents, arranged 
radiantly around the long axis of cell, which lamellae are interrupted 
by it in the middle of the cell.’ From this it will be seen that he 
evidently regarded the central granular mass as the nucleus, while 
the nuclear reticulum was the ‘“mucilaginous envelope.” 
I have described (27) the resting cell of Closterium with special 
reference to ‘the chromatophore and pyrenoids, but have given also 
briefly some idea of the peculiar structure of the nuclei in C. Ehren- 
bergii and C. moniliferum. The particular feature to which I 
called attention was the great accumulation of stainable material 
