PARASITIC FUNGI IN PISHES. 89 



marks, in the First Series of his interesting Glean- 

 ings, " I have observed that when fish have been 

 bruised, or some of their scales rubbed off, a sort 

 of white mothery (from the Moth) matter forms on 

 the place, which invariably kills them. "When it be- 

 gins to form they seldom move ; and if they do, it 

 is by slight darts forward. Their heads get lower 

 and lower, as if they were too heavy for their body ; 

 and when it touches the ground, they turn up and 

 die." This mothery appearance of Mr. Jesse, judg- 

 ing from the investigations which have been made 

 on the silk-worm, is probably not so much the im- 

 mediate effect of external abrasion, as the advanced 

 stage of the disease on which we are now dwelling. 

 Dr. Stark, again, observed this affection in the 

 Stickleback, in the year 1830, and put this inter- 

 rogatory, " Is this the natural death of fishes ? In 

 these fishes," says Dr. S., " when full grown, and, I 

 suppose, arrived at the extremity of age, I have often 

 observed, some days previous to death, the tail ex- 

 tremity to lose its flexibility, and to become covered 

 with a mould, or conferva-like substance, to the 

 height of two or three lines ; and that this substance, 

 or growth, gradually crept along towards the middle 

 of the fish, the rigidity of the parts still increasing, 

 till they died." (Edin. N. Phil. Jour. ix. 331).— 

 Concerning the Carp, Mr. Grifiith, in his learned 

 edition of Cuvier, has the following statement : — 

 " When the carps have attained this very advanced 

 age, they are subject to a malady which is often 

 mortal ; their head and back become covered with 



