172 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
membranes and a lioneycomb-like structure is obtained. The closer 
the fibres the more refractive the membrane. 
The common characters of the intermediate mass of the protoplasm 
and nucleus are shown by the fact that, if the nuclear membrane be 
destroyed or the nuclei have no membrane, no differences of any kind 
can be seen in the apparently homogeneous ground- substance. The 
most essential difference between protoplasm and nucleus lies in the 
presence of chromatin in the latter. By this term chromatin we are to 
understand a substance which stains with numerous colouring matters, 
and in distribution varies considerably. The agglomeration of chromatin- 
grains into small masses is of the highest interest, as it throws light on 
the morphological significance of nucleoli. The origin of nucleoli can 
be very well observed in Sphser echinus. Sometimes there are seen 
spherical parts of the framework which contain regularly distributed 
chromatin-grains ; no membrane can be observed. Other nucleoli 
already show a membrane, and the framework, though as closely meshed 
as in the first, is not so distinctly recognizable. In a third case, though 
certainly present, the framework is difficult to see, and there is here and 
there a tendency to the formation of internal concentric membranes. 
Finally, when the nucleoli are completely developed, there is a highly 
refractive membrane. Just as the nucleoli are formed from chromatin- 
grains, so they may again be resolved into them, for the membranes may 
break up again into fibres. 
The author has succeeded in demonstrating the identity of the bars 
of the framework with spindle-fibres. The contractility of the former 
may be shown by the mode of transportation of spermatozoa in, for 
example, Strongylocen.tr otus from the periphery to the centre. Before 
contracting, part of the fibre elongates, and perhaps breaks at a point 
of attachment. 
Two New and TJndescribed Methods of Contractility in Filaments 
of Protoplasm.* — Prof. J. A. Byder has investigated the peculiar 
phenomena of contractility presented by the stalk of Vorticella and the 
body of Trypansoma Balbianii. The true state of things in the former 
has never yet been adequately described. The muscular filament of 
Vorticella passes downwards through its sheath in a spiral manner, and 
is only in contact along a spiral line with the inside of the transparent 
investing sheath. The filament thus makes eight or nine complete turns 
within its sheath, which is itself not in contact with the spiral muscular 
filament, except along the already mentioned spiral line. If, then, this 
spiral line of contact is in turn traced upon the muscular filament it will 
be found to describe a spiral around the latter. To fully satisfy the 
mechanical conditions of the problem, it is necessary to assume that the 
contractile filament of Vorticella is composed of alternating and super- 
posed discs of singly and doubly refractive plasms. Observations of 
mounted preparations of Carchesium polypinum show that the coiled 
parts of the muscular filament are actually composed of discoidal 
elements, such as are met with in ordinary muscular-fibre. Further 
study showed that the discs of anisotropic matter are in contact along 
the concave or inner side of the coils, and not in contact on the outer 
Proc. Acad. Sci. Philadelphia, 1891, pp. 10-12. 
