15.5 



nearest to the perimysium are poorest in fibres, but are filled with young 

 connective elements derived from the perimysium. The component muscle 

 fibres are swollen and vacuohsed, frequently hardly recognisable. The 

 muscle and connective nuclei are, on the contrary, well preserved. It 

 is interesting to find places where the thickness of the incrustation of 

 leucocytes around the capillaries can be measured. As the capillaries are 

 situated in the perimysium of the fibres, the emigration of leucocytes caused 

 by the inflammation must necessarily follow the fibre perimysium. An 

 invasion of leucocytes takes place between the fibres of the muscle radially 

 around the capillary, forming a ring whose inner diameter is 100 /-'., and 

 whose thickness is of greater or less dimensions according to the size of 

 the blood vessel. The dark, dense net of fibres readily undergoes regressive 

 metamorphosis and prohferation. 



We have shown that under the influence of the oedema the muscle 

 fibres become vacuolised by the formation of fissures and cavities, which 

 are only products of a widening of the intercolumnar spaces : the lesions 

 all point to pronounced lymphangitis. 



The plasmatic substance of the fibrillae, and the fibrillae themselves 

 to a certain extent, dissolves under the influence of pleuro-pneumonia 

 toxine corresponding to the yellow-brown foci of the macroscopic 

 lesions. In fresh specimens one notices here and there processes 

 of hyaline degenerations, and in such cases it is sometimes possible to 

 demonstrate fat by Sudan III staining. The yellow-brown foci, just 

 mentioned, prove on examination to be old stages of the lesions noted 

 above as occurring around blood vessels, but here the blood vessels have 

 proliferated on account of the action of the virus and now form com- 

 plexes of much twisted, recently formed, epithelial tubes. Between the 

 vessel and the incrustation there are a large number of young cells of 

 connective tissue, but the incrustation itself forms a kind of demarcation 

 in which a detritus of nuclei erythrocytes, pigments, blood-platelets, etc., 

 transversed by a few connective fibrillae form a dividing line from the 

 spongy tissue described above. Muscle fibres are nowhere recognisable. 

 A few elastic fibres may perhaps have once belonged to the perimysium. 



This stage is conspicuous on account of the great proliferation of 

 blood vessels and connective tissue. Whether the process could advance 

 further cannot be stated, because animals succumb to the infection at 

 this stage ; it continues in the tail until a cicatrice remains. These lesions 

 are however very rare, usually necrosis takes place before they have time 

 to develop on account of the thrombus in the blood vessels. Around the 

 necrotic detritus, which is very easily stained with eosine or with picric 

 acid, and then appears absolutely structureless, circular layers of blood 

 pigment, and externally to them the usual circu.lar or long oval incrusta- 

 tions of leucocytes are formed. The muscle lying nearest to the necrotic 

 portions are more filled with round cells than those further off. 



