Fishes. 5129 



(twenty-four hours) it had spread over more than half the body, 

 reaching from the nose to the ventral aperture : one was completely 

 dead at 10 a.m., and the other died early next day (30th January). 

 As the plant extended over their bodies they appeared to be stiff, and 

 swam as if moving with difficulty, seeking the top of the water; they 

 afterwards seemed unable to do even this, sank to the bottom, and lay 

 there sluggishly on their sides or in their usual positions : previous to 

 this one of them appeared for a time to become top-heavy, his head 

 sinking down so far as to threaten to turn him completely round on 

 his back, and he made great and evidently painful efforts to regain his 

 usual level condition. After death the plant still continued to grow 

 over their bodies, developing on the snout and over the mouth, and on 

 the fins and tail. 



After a few days the plant manifested itself amongst others of the 

 fish in rapid succession, upwards of half of them dying within twenty 

 days from its first appearance amongst them. Those that last died 

 presented visibly merely the appearance of white films extending over 

 their 'bodies and dangling from their fins and tail, and did not develope 

 during life the full-grown plant, with its tubuli, although in some it 

 became sufficiently evident after death, and reached its perfect state 

 and formed its zoospores. On most of those attacked at this time I 

 noticed red bruise-like marks behind the gills, and especially upon the 

 lower jaw, and in some also on the upper; similar appearances 

 occurred around the ventral aperture, and in two or three upon the 

 sides ; but those first attacked did not present such appearances, nor 

 did those which died more recently. When attacked my attention 

 was usually attracted to them by their rising to the top of the water 

 and swimming in a peculiarly uneasy mariner, as if stiff or pained as 

 they attempted to move ; afterwards they became more and more 

 languid, and sank to the bottom, breathing at longer intervals than in 

 health, and irregularly, and dying usually as if suffocated, with their 

 gill-covers widely distended and the gills visible. 



I may here state that I examined these fish most carefully after 

 death, their gills especially ; the most external of the branchiae were 

 in parts loaded with masses of germinating spores of the plant, which 

 evidently had the effect of destroying their structure and disintegrating 

 them, stripping off the fine lobed capillary processes from the denser 

 cartilaginous structure, and finally loosening the cartilages and re- 

 crossing them. The developed plant consisted of very fine fibres, 

 forming dense interlacing masses, which somewhat resembled the fine 

 nap on velvet. The fibres were of rather tough consistence. Those 

 xiv. 2 D 



