190 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



lateral branches, the extremities of which swell into sacs of a black- 

 ish hue, due to the condensation of their granular contents. Soon a 

 septum forms, isolating the sacs from the little tubes which serve as 

 pedicels to them. After some time the granular matter divides into 

 several masses, which at first adhere to the walls of the sac, but which 

 later become free and spherical. Sometimes there is only one of these 

 masses ; sometimes the same sac contains fifteen or twenty. 1 have 

 fancied that I could recognize on their periphery little mamillce resem- 

 bling regularly arranged opercula.' The sacs have been termed by 

 Pringsheim oosporangia. The oosporangia require fertilization to enable 

 them to produce fertile spores. It is obvious, therefore, that Saprolag- 

 niece have a double mode of reproduction, similar to that of Vaucheria; 

 the one asexual by means of zoospores; the other sexual, producing 

 oogonia arising from the fertilization of a sporangium {oosporangium)? 

 The tubes alluded to in the first portion of this quotation, when de- 

 veloped on the surface of a dead shad-egg, stand out in all directions 

 like a vast number of rays; to make a vivid comparison, the infested 

 egg looks very like a seed-head of the common dandelion, with all of its 

 slight, tufted seeds still adherent to the receptacle. The zoospores 

 alluded to as possessing two hairs or filaments have these latter en- 

 dowed with a power of movement; these filaments in turn propel the 

 body of the spore about, so that in this way the noxious germs of the 

 plants are widely distributed through the water. 



IV. — EXPERIMENTS WITH CARBOLK! ACID TO KILL THE FUNGUS ON 



LARGE FISHES. 



Several hybrid gold-fish in the aquaria in the central station became 

 badly infested with fungus, probably because too large a quantity of 

 dead shad-eggs was thrown into the water to serve for their food, 

 which, instead of being immediately consumed, remained lying on the 

 bottom of the tank until the fruiting condition of the egg fungus was 

 developed on them. These spores from the egg fungus then lodged 

 upon the skin of the fishes and commenced to grow, showing the mode 

 in which the fungoid infection might be conveyed from the egg^ to the 

 adult fish. 



Knowing the fungicidal properties of carbolic acid, it occurred to 

 me to try a very weak solution in water to see if it would kill the fun- 

 gus on the fish. A badly infested fish was placed in a glass aquarium 

 holding nearly four gallons of water; in the first trial ten drops of a 

 concentrated No. 4 solution of carbolic acid was dropped into the water, 

 with little more effect than to make the fish exceedingly restless. The 

 next trial was made by doubling the quantity of acid used, which in 

 the course of ten minutes showed that the fish was suffering and would 

 probably die if fresh water was not immediately turned into the aqua- 

 rium to replace that in which the acid had been dissolved. In a day 

 or so afterwards the fish experimented upon died from the inroads of 



