Proceedings of the Association of American Anatomists XV 
taking on the general form of an hour-glass. At this time the isotropic 
and anisotropic bands are differentiated throughout the entire length of 
the fibrilla. 
Since one observes the fibrillee divided thronghout variable portions of 
their extent and since their number at either end of the myoblast is 
greatly in excess of that at the level of the centre of the myoblast, one is 
led to infer that the mode of increase is longitudinal division. 
The cytoplasmic network, if such it may be called, is exceedingly vari- - 
able, not only in different myoblasts, but also in different portions of the 
same myoblast. Instead of a network one finds a granular matrix filled 
with vacuolar spaces which are highly variable in both form and size. 
The appearances lead one to doubt the existence, in the living cell, of a 
cytoplasmic network. 
That such a network, if it be present in the living cell, bears any defi- 
nite relation to the fibrille is very doubtful. Its meshes must undergo 
marked transformation during the absorption of yolk granules, chang- 
ing from the enormously large meshes, which contain the yolk-spheres, 
to the exceedingly minute meshes containing the fibrille or groups of 
fibrille. Again in conformity to the conical grouping of fibrille, the 
_ meshes of such a network must converge toward the notochordal side, or 
in other words, as the fibrille divide and subdivide the meshes must do 
likewise. This is highly improbable; moreover were it true, we should 
expect to find the smallest meshes at the ends of the myoblast, but this 
is not the case. 
Those who believe in the existence of a cytoplasmic network maintain 
that certain transverse markings of the fibrilla are due to the transverse 
strands of this meshwork. The fibrille when first formed present no 
transverse markings. 
The observations on Necturus lead one to conclude that the fibrillee 
form independently of the so-called cytoplasmic network; the differ- 
entiation of the transverse striations being due to certain portions of the 
fibrilla taking up chromatin or at least a phosphorous-holding nuclein 
as pointed out by A. B. Macallum. . 
ON THE RELATION OF THE THIRD FOETAL SYSTEM OF TREPINSKI 
TO THE DIRECT CEREBELLAR TRACT. By LEewettiys F. BARKER. 
Hull Laboratory of Anatomy, University of Chicago. 
The report referred to the study of two cases of Dr. Sanger Brown’s 
series of hereditary ataxia, and especially to the degeneration of areas in 
the posterior funiculi which correspond closely to the region occupied 
by the fibres of the third foetal system of Trepinski, associated with de- 
