378 Royal Society. 



meter of a globule of the blood. Each of these muscular fibres, of 

 which the diameter is one 400dth of an inch, is divisible into bands or 

 fibrillae, each of which is again subdivisible into about one hundred 

 tubular filaments, arranged parallel to one another, in a longitudinal 

 direction, around the axis of the tubular fibre which they compose, and 

 which contains in its centre a soluble gluten. The partial separation 

 of the fibrillae gives rise to the appearance of broken or interrupted 

 circular striae, which are occasionally seen. The diameter of each fila- 

 ment is one 16,000dth of an inch, or about a third part of that of a 

 globule of the blood. On the other hand, the muscles of organic life 

 are composed, not of fibres similar to those above described, but of 

 filaments only ; these filaments being interwoven with each other in 

 irregularly disposed lines of various thickness j having for the most 

 part a longitudinal direction, but forming a kind of untraceable net- 

 work. They are readily distinguishable from tendinous fibres, by the 

 filaments of the latter being uniform in their size, and punsuing indi- 

 vidually one unvarying course, in lines parallel to each other. The 

 fibres of the heart appear to possess a somewhat compound character 

 of texture. The muscles of the pharynx exhibit the character of ani- 

 mal life ; while those of the oesophagus, the stomach, the intestines, 

 and the arterial system, possess that of inorganic life. The determi- 

 nation of the exact nature of the muscular fibres of the iris presented 

 considerable difficulties, which the author has not yet been able satis- 

 factorily to overcome. 



A paper was also in part read, entitled, " On the Function of the 

 Medulla Oblongata and Medulla Spinalis, and on the Excito-motory 

 System of Nerves." By Marshall Hall, M.D., F.R.S. L. and E., &c. 



February 23. — The reading of Dr. Marshall Hall's paper was re- 

 sumed, but not concluded. 



March 2. — The reading of Dr. Marshall Hall's paper was resumed 

 and concluded. 



The author begins by observing that a former memoir of his, en- 

 titled, "On the Reflex Function of the Medulla Oblongata and Me- 

 dulla Spinalis," published in the Philosophical Transactions for 1833, 

 has been translated into German, and favourably spoken of by Pro- 

 fessor Miiller, of Berlin*. He states that his object in the present paper 

 is to unfold what he calls a great principle in physiology j namely, that 

 of the special function, and the physiological and pathological action 

 and reactions of the true spinal marrow, and of the excito-motory 

 nerves. The two experiments which he regards as aftbrding the type 

 of those physiological phaenomena and pathological conditions, which 

 are the direct effects of causes acting in the spinal marrow, or in the 

 course of the motor nerves, are the following : — 1 . If a muscular nerve 

 be stimulated, either mechanically by the forceps, or by means of gal- 

 vanism passed transversely across its fibres, the muscle or muscles to 

 which it is distributed are excited to contract. — 2. The same result 

 is obtained when the spinal marrow itself is subjected to the agency 



• See our present volume, p. 51 et seq. — Edit. 



