NOTE BY THE TRANSLATOR. 



REFERENCE has already been made to the views of Messrs. Melland 

 and Marshall on the structure of muscle-fibres. The opinion that 

 the striation of voluntary muscle is wholly or in part due to the 

 presence of a regularly arranged network was previously published 

 by Retzius, Bremer, and others. The authors referred to have 

 now for the first time shown the importance of this network in 

 all vertebrate muscular tissues, whether voluntary or involuntary. 



Mr. Marshall gives the following summary of the result of his 

 researches, which the Translator has confirmed by his own obser- 

 vations : 



1 . In all muscles which have to perform rapid and frequent move- 

 ments, a certain portion of the muscle is differentiated to perform 

 the function of contraction, and this portion takes on the form of 

 a very regular and highly modified intracellular network. 



2. This network, by its regular arrangement, gives rise to certain 

 optical effects which cause the peculiar appearances of striped 

 muscle. 



3. The contraction of the striped muscle-fibre is probably caused 

 by the active contraction of the longitudinal fibrils of the intracellular 

 network ; the transverse networks appear to be passively elastic, and 

 by their elastic rebound cause the muscle to rapidly resume its 

 relaxed condition when the longitudinal fibrils have ceased to 

 contract ; they are possibly also paths for the nervous impulse. 



4. In some cases where muscle has been hitherto described as 

 striped, but gives no appearance of the network on treatment with 

 the gold and other methods, the apparent striation is due to optical 

 effects caused by a corrugated outline in the fibre. 



5. In muscles which do not perform rapid movements, but whose 

 contraction is comparatively slow and peristaltic in nature, this 

 peculiar network is not developed. In most if not all of the 



