53 



Tlie Algce of the Bath Thermal Waters. By G. NORSIAN, Esq., M.B. 



(Read December 9th, 1385.; 



The interest attaching to the occurrence of Fresh Water Algae in 

 thermal waters is due, not so much to the discovery of numerous 

 fresh species, as to the mere fact of the existence of Algse under 

 such exceptional circumstances, and of their being able to grow 

 and flourish at a temperature that would be fatal to members of 

 the same genus or even species taken from a normal habitat. For 

 instance, if a portion of Oscillaria were taKen from the canal or 

 river in our neighbourhood and subjected to a temperature of 150 

 degrees it would undoubtedly be kiUed outright, whilst at the 

 thermal springs of Karlsbad, Oscillaria grows freely in water of 

 the temperature of 160". 



Alg£e have been found in many of the thermal springs of 

 Europe ; but the most important one both on account of the heat 

 of the water, and of the variety of genera to be found in it, is that 

 of Karlsbad, already mentioned. Here the calcareous and silicious 

 deposits surrounding the spring are covered with Algse which also 

 line the troughs conveying away the water into the river. In 

 these various situations a large number of genera and species of 

 Alg^ including diatoms are to be found, and some of the species 

 of Oscillaria and Mastigocladus are peculiar to this water. 



At another very hot spring,, the Herculesbad of Mehadia in 

 Austria, no less than nineteen species of Algse have been found, 

 including five species of Oscillaria. These waters are saline- 

 sulphurous in character and vary in temperature from 80° to 

 180^. In the spring itself only a few forms exist, amongst them 

 the Oscillaria — the others are found in the outflow only. 



Closely allied with this is the organic matter found in the sul- 

 phurous thermal waters of the Pyrenees called " Sulfuraire de 

 Fontan" or "Baregine" which has been lately shewn to consist 

 almost entirely of felted masses of Oscillatoria ; this is especially 

 seen at Cauterets, where the temperature is as high as 140°. 

 Numerous Algae have also been observed in and around the 



