58 



Part 111. — Twenty-eighth Annual Report 



nematode is shown (ne.) in a hole in the stomach wall, from which it could 

 not be withdrawn. 



Tumour on the Tail of a God (24th November, 1909). 



The tumour was a red-coloured mass projecting as a round swelling from 

 the side of the fish just above the second anal fin (hi., fig. 61). It was 

 covered up with a soft white layer which has been formed by the coagulation 

 of the secretion poured out of the sore. 



The coagulated secretion extends on to the skin on both the anterior and 

 posterior sides of the tumour. Underneath the secretion the derma is 

 bleached. Anterior to the point p. (fig. 58) the pigmentation is normal. 



When the sore was pressed a thickish and pale white fluid was poured out. 

 The tumour was then like a sponge, from which the matter oozed at various 

 openings. The secretion coagulated in water. 



Under the microscope this fluid is seen to be composed of a granular fluid 

 in which are yellowish rod-like or spindle-shaped bodies, apparently crushed 

 and disorganised blood corpuscles, and pale round corpuscles containing 

 bright granules. 



A longitudinal section of the tumour is shown in fig. 58. The derma is 

 thickened beneath the sore ; the channels crossing this layer obliquely are 

 very wide, they apparently give passage to blood-vessels. The connective 

 tissue layer between the derma and the muscles is also much thickened and 

 supplied with large blood-vessels. The cuticle is absent. The scale-pits 

 (scp.) are enormously increased in size. They are filled up with a much- 

 folded and branched ribbon-like frill (fr.). This frill is red, and it is well 

 supplied with blood-vessels. The loops formed by the latter are well seen 

 at the top edge. The frill is dotted all over right down to the bottom of 

 the scale-pit with little black pigment spots. Its surface is covered, in 

 parts at least, with little short tubules (fig. 62) which are arranged so closely 

 that the tissue resembles a skin covered with hairs. In end view they 

 appear round, with a circle which might be either a pore or a nucleus visible 

 within them. In side view an oval body is seen within, near the tip. The 

 little tubules break off and are found free in the secretion that is 

 pressed out. 



The frill is scalloped and is sub-divided into numerous irregularly-shaped 

 pieces. It secretes the fluid, which lies between the folds, and collects in the 

 middle of the scale-pit. In fig, 65 a -surface view of a part of the tumour 

 exhibits the frill (fr.) and the secretion (se.). Where the secretion is forced 

 out of the tumour, the pits are completely filled up by the frill. 



In the centre of the sore the inflammation and extra growth are inside the 

 scale-pits. The latter are very large. In one, at least, a small scale was 

 found. The scale in some pits is partially eaten away. 



On the posterior side (%>ost. fig. 58), beneath the secretion, the papillae of 

 the derma (pa.) are lengthening and becoming suffused with blood. They 

 would eventually develop into frills I believe. The scale-pits posteriorly 

 show a reddish hue. 



In the derma the gland openings occur as very little clear spaces in the 

 pigmented outer layer. Near the tumour these glands are enlarged and the 

 region is slightly reddish. 



The skin of the trunk along the base of the anal fin seemed to be drawn 

 to some extent, but was not affected. 



The tumour may have arisen in consequence of something having adhered 

 tightly to the skin, to which it remained attached long enough to cause local 

 inflammation. The secretion from the tumour can evidently cause this, as is 

 shown by the condition of the skin at the edge of the tumour. The 

 inflammation has resulted in the development of the frills from the derma 

 both inside and outside the scale-pits. 



