50 A. R Hardy: 



*Soiue tadpoles succumbed to the disease, and these had the 

 same disorganised mouth parts, etc., but no visible Sapro- 

 leynia or Alga, and therefore, keeping in mind J. Hume Pat- 

 terson's statement' that B. .salmon is pestis is not pathog'enic to 

 frogs, it seems probable that B. pisricldus hipolaris, Greig, 

 would be found on bacteriological investigation. 



The presence of M i/ronema tenue appears to depend on the 

 ;preceding groAvth of the fungus, in the mycelium of which 

 zoospores of the former may be enmeshed. In the Yarra 

 iRiver, above Dight's Falls, this species occurs as long streamers 

 in the current, attached to willow, twigs, etc. In the wooden 

 ,£umes of the Kew fish-ponds it attained in January a length 

 of 22 cm., and in the ponds there was a sickly growth, the 

 l^oor development being evident both in reduction of size of 

 the plants and richness of colour of chloropjasts, etc. The 

 plants on the tish, though very small, were vigorous and rich 

 in colour, while some of the branchlets were actively producing 

 zoospores at time of collection. Tlie suggestion made in my 

 •previous paper that this stream-loving plant iidapts itself to 

 •comparatively stagnant Avater by securing a foothold on a 

 motile substratum, seems to hold good. 



The Fisheries Branch of the Ports and Harbours Department 

 lost no time in constructing sunshades, and by thus lowering 

 the temperature and by cleansing the reservoir, which will 

 ^probably be kept at high level, has reduced the trouble in the 

 course of a few months almost to the vanishing point. 



One of Huxley's determinations, in 18.S2, was that the facts 

 ■ obtained iii his investigations were not favourable to the sup- 

 position that either pollution or overcrowding had much to do 

 -with the matter, and again, that we could not n)ake progress 

 until the relationship between the sporadic and epidemic phases 

 of the disease, as affecting salmon, became known. The mention 

 of salmon disease in the Fraser River, British Columbia, and 

 in the Castries Kiver, Siberia, does not, for climatic reasons, 

 affect the present case. I hav^ endeavoured to show that, given 

 pollution and high tem]>erature, there is great danger, and 

 that the trouble has been almost removed by reducing these to 

 normal conditions. 



