HARDWICKE'S SCIENCE-GOSSIP. 



>3* 



and hairs of cat and mouse, also desmids and 

 diatoms, shreds of dry wool and cotton, with other 

 fragments of matter unknown to me." 



With all due deference to Mr. Stirling I feel bound 

 to remark that although the fish in its efforts to get 

 rid of the parasite does lacerate itself, still the skin is 

 already completely disorganised by the operation of 

 the fungus. Soft-bodied animals, as tadpoles, when 

 attacked are penetrated throughout by the mycelium 

 of S.fcrox, and the whole substance of the creature 

 is interwoven with its threads. In addition to the 

 debris detected by Mr. Stirling other impurities are 

 indicated, as the following extract from a newspaper 

 communication well shows : 



" Certain kinds of chemical impurities are known 

 to be favourable to the growth of fungoid life, and the 

 practice of sheep-washing, which is largely carried on 

 in the rivers of the south of Scotland, the use of 

 artificial manures, washed by the heavy rains and 

 melting snows of the past winter, and the existence 

 in the streams of various polluting matters from 

 factories and towns, are very likely to have combined 

 to produce the condition favourable to the present 

 outbreak." 



Again, salmon in rivers are subject to artificial 

 conditions, and cannot carry out their natural instincts. 

 In evidence of this assertion Mr. F. Buckland writes : 

 " A large number of fish which have done spawning 

 are moved by their instinct to get down as quickly as 

 possible to the sea, but they cannot do so on account 

 of their journey being delayed by the weirs and 

 ' caulds ' on the Tweed and her tributaries. The 

 instinct of the invalid salmon teaches them to go to 

 the sea because it is certain the fungus cannot exist 

 in the sea ; and secondly because they wish to pick 

 up condition and fatten upon their natural food, which 

 consists of sand eels, sprats, herrings, smelts, and the 

 fry of other sea-fish. When the fish are delayed 

 above the weirs, the crowding tends to disseminate 

 the disease, for I am sure the fungus is catching." 



Whatever therefore may be the cause of the disease, 

 the fact stares us in the face, that crowding above the 

 weirs most certainly tends to foster and spread its 

 ravages, just as when pilgrims at Mecca become too 

 crowded the plague is started and spreads. Mr. 

 Buckland here asserts positively "that it is certain 

 the fungus cannot exist in the sea," its development 

 may be checked, but it is questionable if the vitality 

 of the resting spores would be impaired by continual 

 immersion in sea water. The salmon recovery may 

 also be due to improved feeding, and hence tone and 

 increased vitality, which enables the fish to resist the 

 encroachment and ultimately rid itself of the parasite. 

 I once tried a little experiment with sticklebacks ; of 

 these I had a dozen or so, all more or less affected 

 with the fungoid growth. I transferred them from a 

 freshwater aquarium to sea water (sticklebacks live 

 well in sea water after getting accustomed to the 

 difference of density), but although their existence 



might be somewhat prolonged, the fungus ultimately 

 reached their gills and killed them all. 



The excessive protection afforded to many species of 

 game, and unmitigated destruction of so-called vermin 

 which naturally clear off the sickly and weak, appears 

 to induce many hitherto unknown maladies among 

 them. Such diseases do not confine their ravages to 

 the point of origin ; usually contagious, they extend 

 their limits and include both strong and weak in a 

 common destruction. 



So with salmon, it may be that in artificial fish 

 hatching and rearing a large percentage of weakly 

 fish reach maturity which in an ordinary way would 

 have succumbed to their natural enemies. Such 

 would be the first seized by the fungoid parasite in 

 question and of necessity convey the contagion to 

 others. An outbreak so excessive can only be ascribed 

 to some general cause, as it is scarcely reasonable to 

 suppose that the contaminated rivers became polluted 

 all at once. Where the disease appears, each infected 

 fish becomes an agent of destruction to its kind, and 

 an assiduous emissary in disseminating myriads of 

 motile and resting spores, all seeking or waiting for 

 the condition essential to development. 



The question of chief interest to microscopists 

 appears to be :- How does the parasite establish 

 itself upon the animal, and in what manner is the skin 

 impregnated by its spores ? No doubt a scratched or 

 abraded surface would readily meet the requirements 

 of the fungus, but in the absence of such preparation, 

 it is highly probable that the motile spores are 

 introduced by absorption. Something analogous 

 exists in the human family, and the terrible malady 

 known as the fungous foot of India, prevalent amongst 

 the shoeless portion of the population, affords an 

 example. This fungus, resembling a Mucor, but 

 scientifically classed as Chionyphe Carteri, perforates 

 and honeycombs the bones of the foot, the cavities 

 becoming filled with the mycelium of the plant, when, 

 if speedy amputation is not effected, death soon ensues 

 from exhaustion. Mr. H. J. Carter, F.R.S., is of 

 opinion that this disease is occasioned by the entrance 

 through the sudorific ducts of minute spores in an 

 amoeboid state and which attain a monstrous growth 

 as the black fungus in the human body. 



It is certainly within the microscopist's province to 

 ascertain and accurately describe the character and 

 habits of these destructive pests. When the condi- 

 tions under which they flourish are once known, such 

 may be removed and the foe ousted from its source. 



But to deal empirically with an enemy like this, or 

 when known to adopt merely vacillating measures, is 

 to trifle with a destructive and insidious antagonist 

 with the probable result of rendering the mischief 

 chronic. Although epidemics amongst preserved 

 animals seem usually to run their course and vanish 

 for a time, as with the civilised portion of humanity, 

 yet a primary cause must exist to account for each 

 outbreak, probably resolving itself in its origin into 



