407 



orange coloured Algae and iron was being deposited. I have also 

 met with cylindric casts of roots, in haematite. One of these casts 

 is h an inch in diameter and perforated by a tube one-tenth of an 

 inch across evidently corresponding to a root since decayed. 



A similar case of the formation of iron-pan by an Alga (Gaillo- 

 nella) is mentioned by Lyell in his Geology, and it is possible that 

 all these oxide of iron deposits are caused by Algae, or Bacteria. 



I have called this plant an Alga and some Botanists consider it 

 so, but De Bary and others class it as an Arthrosporous Bacterium. 

 The figure he gives of Crenothrix Kuhniana, (Morphology and 

 Biology of Fungi, p. 470 fig 196) considerably resembles this plant, 

 but appears to be bigger and it is difficult to see the characteristic 

 breaking up of the filaments figured by him in the Singapore plant. 

 The cocci and zoogloea forms are however quite similar. He men- 

 tions it as a Schizomycete which occurs frequently in water contain- 

 ing some amount of organic substances and sometimes in quantities 

 which are dangerous to health, and indeed it seems to be a most 

 objectionable plant in water. 



Crenothrix ,is not the only Alga which gives an orange coloring 

 to the water here, as on the Enhydrias and on Utricularia, I 

 found an abundance of fusiform Diatoms of a reddish yellow colour, 

 which were arranged in strings one over-lappihg another, which 

 gave an orange colour to the leaves of the weeds. It appeared to 

 be a species of Pleurosigma. 



It has been said that ponds have been completely cleared of 

 Algal scum in Ceylon and elsewhere by the use of copper sulphate 

 in such small quantities that animal life is not injured and the water 

 remains purified and fit for human use. This apparently is not 

 efficacious hi re. The quantity of copper sulphate required to pre- 

 cipitate the Crenothrix , is too great to be safe to use, and in ponds 

 with shallow shaded edges the plant grows so rapidly that in a few 

 days it is as bad as before. It can also apparently thrive under 

 ground in water following the courses of roots so that it can be 

 conveyed through springs, growing along the roots. 



Action of Copper sulphate on other aquatic plants — A quantity of 

 Utricularia stellata growing in the Garden's Lake was taken and 

 put into two jars filled with water as in the case of the Crenothrix. 

 One jar was treated with copper sulphate ^ f oz. to the jar. The 

 other untreated. The Utricularia was swarming with rotifers, para- 

 mcecia, minute larvae and other animals, besides containing numerous 

 diatoms, desmids, and other Algae of different kinds. The day after 

 the copper sulphate was added, a good deal of the Utricularia was 

 found to be dead and there were no signs of animal life except at 

 first a few Paramcecia. Dead insect larvae were seen at the bottom 

 of the jar. In the untreated jar the rotifers, vorticellas and other 

 infusoria were lively and thriving and the Utricularia was green 

 and healthy. 



A remarkable thing noticed about this Utricularia was that the 

 older bladders, apparently those that had caught infusoria, were of 



