1704 
ON SIMPLE STRIATED MUSCULAR FIBRES, 
ON SIMPLE STRIATED MUSCULAR FIBRES. 
By William A. Haswell, MA., D.Sc., Lecturer on Biology, 
Sydney University. 
A comprehensive study of striated muscular tissue as it is 
exhibited throughout the various classes of the animal kingdom 
appears to lead to the conclusion that there are two main types 
not in any way directly related to one another, distinguishable 
among the fibres which are classed together generally as striated. 
Of these the one— the compound type of fibre— I have dealt 
with elsewhere as regards its structure and distribution. The 
present paper contains some observations on the second or simple 
type of fibre. 
These simple fibres differ for the most part only in the presence 
of transverse striations from the non-striated fibres of the same 
animal ; they are of the same, or nearly the same, thickness as the 
latter, are not more readily split into longitudinal elements, and 
each consists, almost invariably, of a single cell. The sub-stance of 
such fibres is, however, transversely striated ; it is marked by 
regularly arranged transverse lines or bands, which may be visible 
in the fresh condition or may only be brought out by the action of 
staining agents ; in some instances the striation may be due to 
the division of the fibre into a series of alternating bands or discs 
of different optical properties, such as are presented by the mus- 
cular fibres of the compound striated type ; but of the presence in 
any simple striated fibre of transverse networks, such as charac- 
terise the compound fibres, I have not been able to find sufficient 
evidence. 
