156 THE NORTHERN MICROSCOPIST. 

tremities. The effect of the growth of the stem hyphee is to destroy 
the epidermis altogether. Its place is taken by a thick felted my- 
celium which entangles the minute particles of sand suspended in 
the water, no doubt constituting a very irritating application to the 
sensitive surface of the true skin. When the fungus was found 
penetrating the true skin and gaining access to the lymphatic 
spaces and blood-vessels, it was of interest to ascertain whether 
the hyphe might not break up into toruloid segments, as in the 
case of Hmpusa musce, and then give rise to general septic poison- 
ing, but the occurrence of such a process was not observed. 
A very important practical question arises from the discovery 
that the fungus penetrates into the derma. There is much reason 
to believe that if .a diseased salmon returns to salt water all the 
fungus which is reached by the saline liquid is killed, and the des- 
troyed epidermis is repaired, but the sea water has no access to the 
hyphz which have burrowed into the true skin, and hence it must 
be admitted as possible that in the case of a salmon which has 
become to all appearance healed in the sea, the remains of the 
fungus in the derma may break out from within when it ascends 
the river, and the fish again become diseased without any fresh in- 
fection. 
Prof. Huxley’s general observations have led him to the follow- 
ing conclusions :— 
1. That the Saprolegnia attacks the healthy living salmon 
exactly in the same way as it attacks the dead insect, and that it is 
the sole cause of the disease, whatever circumstances may, in a 
secondary manner, assist its operations. 
2. That death may result without any other organ than the skin 
being attacked, and that, under the circumstances, it is the conse- 
quence partly of the exhaustion of nervous energy by the incessant 
irritation of the felted mycelium with its charge of fine sand, and 
partly by the drain of nutriment appropriated by the fungus. 
3. That the penetration of the hyphe of the Safvolegnia into the 
derma renders it at least possible that the disease may break out in 
a fresh-run salmon without re-infection. 
4. That the cause of the disease, the Safrolegnia, may flourish in 
any fresh water, in the absence of salmon, as a saprophyte upon 
dead insects and other animals. 
5. That the chances of infection for a healthy fish entering a 
river, are prodigeously increased by the presence of diseased fish 
in that river, inasmuch as the bulk of Saprolegnia on a few diseased 
fish vastly exceeds that which would exist without them. 
6. That as in the case of the potato disease, the careful extirpa- 
tion of every diseased individual is the treatment theoretically 
indicated ; though, in practice, it may not be worth while to adopt 
the treatment. 
