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SUMMARY OF CURRENT RESEARCHES RELATING TO 
Structure of Unstriped Muscle.* — Herr Josef Schaffer has made 
an exhaustive series of observations on this subject, with a special view 
to determining the relations of the cells, and the presence or absence 
of the “ intercellular bridges ” of Kultschitzky. He began his investi- 
gation with fresh preparations from the umbilical cord, gut, and urino- 
genital tract of man and domestic animals. Such preparations showed 
the existence of a partly fibrous connective tissue between the muscle- 
cells containing formed elements. The margins of the muscle-cells 
were perfectly smooth, and the appearance of transverse bridges across 
the cells was due to folds in the connective tissue or to fibrous structures. 
A series of experiments with fixing reagents then showed that these 
alter greatly the appearance of the cells, and that the same reagent 
does not necessarily act alike upon all muscle preparations. Usually 
the effect of the reagents is to make the smooth contour of the cell 
appear toothed. In studying sections, allowance must be made for such 
changes of structure ; and the stains employed should differentiate 
between muscle-cells and connective tissue. A mixture of picric acid 
and acid fuchsin was found to do this. A comparison of numerous 
preparations stained in this w 7 ay showed that a delicate perforated sheet 
of connective tissue exists between the muscle-fibrils. This has really 
a foam-like structure, but in optical section appears like a network of 
fibres. The “ intercellular bridges ” of Kultschitzky and Barfurth are 
artificial products due to the rupture of this intercellular connective 
tissue. This result explains the contradictory results obtained by 
various authors as to the presence or absence of “ intercellular bridges ” 
in the unstriped muscles of different animals. 
Intercellular Connections and Cell Prolongations, j* — Herr F. K. 
Studnicka publishes an elaborate paper on the relations between the 
two kinds of cell prolongations, those which project from the free 
surface of the cells (cilia, striated membranes), and those which con- 
nect adjacent cells (intercellular bridges, &c.). He endeavours to 
prove that such a relation exists by an exhaustive comparison of the 
results obtained by himself and others from the investigation of the 
two kinds of structure. Intercellular bridges are those prolongations 
which connect the adjacent cells of epithelia, notochordal tissue, &c., 
by bridging over the intercellular spaces. The bridges are some- 
times filiform and at other times lamelliform, and are either smooth or 
furnished with little swellings. The author then describes in detail 
the intercellular structures found in epithelia, in unstriped muscle, in 
connective tissue, and in cartilage. As to the meaning of the inter- 
cellular spaces, the author notes that they are present in epithelia, in 
notochordal tissue, and in unstriped muscle (but cf. Schaffer above), 
except in young cells or where a matrix occurs between the cells. They 
communicate with the lymphatic system, and probably serve to nourish 
the cells. The intercellular bridges are elastic and are capable of con- 
traction and expansion, they are plasmic and so at least primitively 
connect the plasm of adjacent cells, but in some cases they originate 
from the hardened exoplasm of the cell and appear to be quite passive. 
Their existence is not therefore an argument against the cell theory. 
* Zeitechr. f. wiss. Zool., lxvi. (1899) pp. 214-68 (2 pis.). 
f SB. Bohmisch. Ges. Wiss., 1898, pp. 1-66 (1 fig.). 
