458 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VoL. VI. 
adjacent to the transverse septa, the membranous bands separating the 
vesicles in the neighbourhood of the septa are shorter than elsewhere. 
The bands terminate in a thin delicate layer closely applied to the cell 
membrane, which can be seen with difficulty and is most evident when, 
as in Oscillaria Froehlichii, it is,as in that part adjacent to the transverse 
septa, rich in granules of the “cyanophycin” class. The latter are 
usually at “ nodal” points of the layer and membranous bands termina- 
ting in it. The layer may sometimes be distinctly seen in preparations 
of Osctllaria Froehlichit which have been hardened in alcohol and 
stained with haematoxylin. In these the cytoplasm has shrunken away 
from the membrane at one side of the cell in many trichomes and in this 
case the thin hyaline layer, stained somewhat more deeply than the 
enclosed cytoplasm, appears sharply contrasted with the latter. 
In Oscillaria natans, Tolypothrix tenuis, Scytonema sp., and in the 
vegetative cells of Cyndrospermum mazus the structure of the cytoplasm 
in the fixed condition is the same as in Oscztllaria Froehlichiz. In these 
forms, however, the cells are much smaller and consequently the 
vesiculation, which may be clearly observed in the larger form, is only 
rarely well seen. On the other hand the distinction in the cytoplasm 
of a central body and a peripheral zone is quite as readily marked as in 
the large forms of Osczllart@. The central body also stains in hema- 
toxylin more deeply than the peripheral cytoplasm, into which it is con- 
tinued without any sharp transitional changes in staining or structure. | 
In Wicrocoleus terrestvis owing to the narrow transverse diameter of 
the trichomes the differentiation of the cytoplasm into a central body 
and a peripheral zone is not perceptible. There is a difference between 
the most centrally placed cytoplasm and that of the periphery, but where 
one begins and the other ends it is impossible to say. The most 
centrally placed part stains more deeply in haematoxylin than does the 
peripheral part and at the same time appears denser. Vesiculation in 
both parts has been often observed but there is no distinction in the size 
of the vesicles of the two parts. In thecentral part more of cytoplasmic 
substance appears to surround each vesicle when the vesiculation is 
distinct. In Oscillaria tenerrima there is apparently no distinction 
between central part and peripheral layer, except in the deeper staining 
of the more central cytoplasm. Vesiculation was not observed in this 
form. (Fig. 16). 
These facts support on the whole Biitschli’s claim that there are two 
parts, a central and a peripheral, and that the character of the latter is 
different from that of the former.  Biitschli’s view that the central 
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