[ 457 ] 
XXL On the Minute Structure and Movements of V oluntary Muscle. By William 
Bowman, Esq. Demonstrator of Anatomy in Kings College, London, and Assistant 
Surgeon to the King's College Hospital. In a Letter addressed to Robert Bently 
Todd, M.D. F.R.S., Professor of General Anatomy and Physiology in King's 
College, London. Communicated by Professor Todd. 
Received June 18, — Read June 18, 1840. 
My dear Dr. Todd, 
In offering to your notice the following account of some researches into the minute 
structure and movements of voluntary muscle, which I commenced at your sugges- 
tion, and in the prosecution of which you have so materially aided me, I am encou- 
raged to hope that some parts of the inquiry may not be altogether uninteresting to 
the Royal Society, to which the first discoveries in this important branch of physiology 
bv Robert Hooke and the illustrious Leeuwenhoek were communicated, and which 
also possesses, in its later Transactions, important papers on the same subject. 
It has long been known that voluntary muscle is susceptible of subdivision into 
minute threads, which being almost uniform in size, unbranched, and united by means 
of vascular and cellular parts into bundles of varying bulk, have generally been re- 
garded as constituting the essential proximate anatomical element of the organ. 
All the best observers, since the time of Leeuwenhoek, have recognised the existence of 
these threads, but their form and composition have been objects of continual dispute, 
and in the present day w T e seem to be as little advanced towards the determination 
of their real nature as ever. The improvements which have taken place in the con- 
struction of microscopes, appear indeed to have only afforded grounds for new differ- 
ences of opinion, as may be seen by the records of the last few years. In 183/ 
Mr. Skey, after an elaborate investigation, concluded that these threads were tubes 
containing a soluble gluten, round which were disposed, in longitudinal sets, still finer 
filaments, which in their turn were held together by circular bands or striae ; and 
since that period, Dr. Mandl, a microscopical observer in Paris, has described and 
figured them as bundles of fibrils, held together by a spiral coil of filamentous tissue. 
A more common opinion is, that these threads are bundles of beaded fibrillee, whose 
beads being placed side by side, cause the appearance of transverse lines, a view which 
was first entertained by Fontana, though his claims to it have been often overlooked. 
More lately Dr. Schwann and M. Lauth have advocated the same doctrine, especially 
the former, who has adduced additional arguments in its support. 
My design in the present paper is , first, to vindicate, under certain modifications. 
MDCCCXL. 3 N 
