887 



stained and which is easily distinguished from the homogeneous masses in the 

 "Zenker" degeneration. 



This degeneration principally occupies the circular fibrils, which are often already 

 quite changed into very small threads and grains while the central fibrils are still 

 normal. 



In many fibres the figure becomes still more intricate, because bundles of 

 longitudinal fibrils are visible between the circular ones. This phenomenon sometimes 

 appears to such an extent, that we can call it a real twisted- work. This twisted- 

 work is generally only to be seen in the peripheral fibrils, but may also occur in 

 the central part of the fibre. 



The twisted fibrils always show signs of degeneration and it is a general 

 rule that: the more the figure is intricate, the more the degeneration is advanced. 



These pathological changes are nearly always accompanied by thickening of the 

 muscle fibre, which may become so extensive that a diameter of 250 X 250 fi in 

 transverse sections is not uncommon. 



With this kind of degeneration there is not much activity of the nuclei; in some 

 spots they have become more numerous, but accumulations of nuclei as in the 

 fibres with "Zenker" degeneration were not to be seen. 



Although the muscle-knob seemed to be distinctly contrasted with the surround- 

 ing tissue, microscopical investigation showed us the presence of divers degenerated 

 fibres and also fibres with a mantle of circular fibrils in the immediate vicinity. 



With the exception of the above described groups of cells in the connective 

 tissue no signs of inflammation were apparent ; these cells have probably something 

 to do with the evacuation of rests of degenerated muscle fibres ; we may therefore 

 not deduce from this that it is a process of inflammation. 



We looked carefully for the presence of bacteria, protozoa and of other para- 

 sites, but without result, i) 



The microscopical examination of the brain, the spinal cord and some peripheral 

 nerves showed nothing interesting. 



Some viscera were examined, but these neither showed any abnormities. 



Among the different pathological changes which were present, we must 

 pay special attention to the numerous peculiar muscle fibres, which in 

 transverse sections seem to exist of two concentric parts, the exterior part 

 containing circular fibrils, the interior part containing longitudinal-ones. 



How can this figure be explained? 



As in the beginning I could not find in the literature anj' de- 

 scription of these changes, nor any connecting statement w hich made 

 it possible to explain them, 1 was inclined to think that these 

 changes could possibly be connected with the peculiar structure 

 of the muscle fibres of fishes, which normally already show a 

 difference between the centre and the periphery and to consider 

 this stucture as the cause of these curious changes. 



1) I wish to express my gratitude to Mr. J. H. Schuurmans Stekhoven Jr., 

 interem-zoologist of the institute for Tropical Hygiene at Amsterdam, for his kind 

 help with this part of my investigations. 



