Report on Diseases and Abnormalities in Fishes. 17 



tibrillse arc bathed in a clear plasma crowded with spore-blasts and 

 free spores. The muscle fibres are quite normal. They have not 

 been affected by the parasite. The latter does not feed on the 

 muscle fibres. The sporoblasts all seem to be of one stage. They 

 do not appear to be multiplying' in the fibres. They are probably 

 formed elsewhere in the body of the fish, and are deposited in the 

 muscle fibres. 



The spore is pear-shaped (fig. 59b). It is about -005 mm. by 

 003 mm. The spores are of two sizes. Hofer's drawing of the 

 muscle bundle infected with Myxobolus Pfeiferi recalls the condi- 

 tion here described (fig. 5 9) . The spore of that sporozoan, however, 

 had two polar vesicles. A diagram of a section of the 

 tumour is given in fig. 101. In the centre several myotomes 

 are composed of brown fibres (&.), while at the periphery the fibres 

 are white (ivh.). Between the two a myotome consists of both 

 brown and white fibres. The tumour is evidently extending at its 

 periphery, and the normal fibres are being attacked. The brown 

 fibres are dried up. They are about 35 mm. broad and about 

 4 mm. long. They enclose the sporoblasts. When freed by teas- 

 ing the spores seem to be similar to those got from the white fibres. 



The tumour was mainly on one side of the dorsal region, but it 

 extended through, by the space between the dorsal and vertebral 

 spines, to the other side of the body. This small continuation had 

 also a brown centre, showing that it had originated simultaneously 

 with the larger portion. A smaller tumour occurred in the muscles 

 a little apart from the large tumour. 



No sporoblasts were found in the red fluid of the kidney. This 

 is evidently the same disease which affected a Zoarces viviparus 

 recorded in a previous paper (published 1911). This fish showed 

 a number of tumours in the trunk muscles. A part of one of the 

 tumours was sectioned by Dr. F. M. Milne, Dundee. Fig*. 43 

 represents a small portion of one of the sections. The sporozoan 

 (spo.) seen is occupying a position inside the muscle fibre (m.). It is 

 evidently a collection of sporoblasts. Fig. 47 shows a portion still 

 further magnified, Spo. represents a sporoblast, and m. the muscle 

 hbrillse. 



The swollen muscle fibres described above recall the condition 

 known as Miescher's tubes. According to Braun, Miescher and 

 Hessling considered them to be pathological transformations of the 

 muscles. Bertram described the Miescher's tubes found in the muscle 

 of the pig, viz., Sarcocystis miescheri, R. Lankester [? Sarcocystis 

 miescheriana (Kuhn)]. When fully developed it is between '5 and 3 

 mm. in length, and '4 mm in breadth. The chambers of the tube are 

 filled with balls of sickle-shaped bodies. In their protoplasm there 

 are dark " Kornchen," usually two vacuoles, and a nucleus. As soon 

 as the Sarcocystis enters, a deposition of calcium salts may take place 

 in the tubes and surrounding them. 



As shown above, the muscle fibres may be swollen in two ways — 

 first, by the collection in them of lymph, and, secondly, by the 

 deposition in them of the sporoblasts of a sporozoan. 



Linton describes a case of sporozoan infection of the muscle of the 



herring. Drew records a case where the muscles of the cod were 



invaded by a new species of Pleistophora. In the muscles there were 



diffuse pigmented areas of a brown colour. The muscle tissue in the 



n 



