Mettam — Malignant Tumours in Birds. 71 



Pieces of the tumour were removed and fixed in 10 per cent, formalin in 



water or in acetic acid sublimate solution. Fixation being complete, the 



tissues were washed for twenty-four hours in running water and then 



passed through spirit, absolute alcohol, alcohol-xylol, xylol-paraffin, into pure 



paraffin and thence imbedded. Sections were made and fixed on albuminised 



slides and brought down, after drying, to water. They were then stained 



either by 



Hsematoxylin and eosin, or 



Hsematoxylin and van Gieson's mixture, or 



Iron alum hsematoxylin, or 



Methyl blue and eosin (Mann's method), or 



Magenta-Cajal (Podwyssotsky's formula). 



After dehydration and clarifying they were mounted in balsam. 



Microscopic Examination. — The tumour is a small, round cell sarcoma. 

 The cells generally are round, save where mutual pressure has deformed 

 them. They average from 7 to 8 yu in diameter. The nucleus, relatively large 

 to the size of the cell, is surrounded by a small amount of protoplasm, without 

 granules. The nuclear membrane is distinct, with a delicate nuclear network, 

 with a moderate amount of chromatin. Mitosis is not common, though 

 examples are found without much difficulty. The amount of connective 

 tissue is small, and the fibrils are very delicate. The blood-vessels are badly 

 defined ; the walls are embryonic, and in some places not recognizable. There 

 are no signs of recent large haemorrhage, though in the sections small 

 accumulations of corpuscles, without any apparent restraining wall, are to be 

 seen. It is possible these may be haemorrhages, though, as is well known, in 

 the sarcomata the vessels in many cases have practically no walls other than 

 those formed by the tumour-cells. 



Sections of the new growth invading the lung show that the new growth 

 has almost wholly replaced the lung-substance ; here and there remains may 

 be found, as, for instance, the outline and epithelium of a large bronchus. 

 In one bronchus sections of a worm were found. The lung had been wholly 

 destroyed as a respiratory organ. Where the tumour had invaded a muscle, 

 the tumour-cells were found to be infiltrating in enormous numbers. 

 Pushing aside the muscle fibres by their pressure, they induce atrophy and 

 eventually destruction of the muscle fibre. In some places the tumour-cells 

 were found within the sarcolemma, bursting up the muscle fibre and causing 

 its entire disappearance. 



In certain places in the sections the tumour-cells were observed to contain 

 inclusions ; and I am not aware if such inclusions have been hitherto 

 described in sarcomatous cells. They are well known, as previously 



