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XIII. " Researches into the nature of the Involuntary Muscular 

 Fibre." By GEORGE VINER ELLIS, Esq., Professor of 

 Anatomy in University College, London. Communicated 

 by Dr. SHARPEY, Sec. R.S. Received June 11, 1856. 



(Abstract.) 



Having been unable to confirm the statements of Professor Kolliker 

 respecting the cell-structure of the involuntary muscular fibre, the 

 author was induced to undertake a series of researches into the nature 

 of that tissue, by which he has been led to entertain views as to its 

 structure in vertebrate animals, but more especially in man, which 

 are at variance with those now generally received. The present 

 communication contains the results of these inquiries, which tend to 

 show that the voluntary and involuntary muscles resemble each 

 other very closely in the arrangement and constitution of their 

 fibres. 



After adverting to the present state of opinion on the subject, the 

 author gives an account of his own observations, and treats successively 

 of the interweaving of the fibres, their size, form, and ultimate 

 structure ; their mode of attachment at their extremities, their length, 

 and the corpuscles connected with them. He devotes a section also 

 to the question of the periodic formation and destruction of muscular 

 fibres in the uterus, in its different conditions ; and while he is led 

 by his own investigations to recognize an enlargement in size of the 

 individual fibres of that organ during pregnancy, followed by subse- 

 quent diminution, he is unable to confirm the doctrine of new forma- 

 tion. Moreover, he finds that during pregnancy a considerable 

 amount of granular matter, with round or oval granular-cells, is 

 deposited among the fibres. He adduces reasons for believing that 

 this substance cannot be regarded as a blastema, nor its imbedded 

 cells as formative cells, for the production of new fibres ; and he is 

 disposed to ascribe the enlargement of the uterus in pregnancy prin- 

 cipally to the enlargement of the muscular fibres, and the addition of 

 this new deposit. 



