On Animal and Vegetable Life in the Water of Leith. 233 



II. On the Animal and Vegetable Life in the Water of Leith, &c. 

 By Dr Stevenson Macadam, F.R.S E. 



In the bed of the Water of Leith above the influence of 

 the sewage of Edinburgh, as at Gorgie dam, which is about 

 a mile above Coltbridge, the stones over which the water 

 flows have plants, such as moss, attached to them, and these 

 plants are found on the stones in the bed of the streams con- 

 veying water practically free from putrescent matter ; but 

 from the entrance of the Edinburgh sewage at Coltbridge 

 downwards to the harbour of Leith, the stones in the bed of 

 the stream are covered with offensive organic growths, which 

 are characteristic of waters conveying sewage and capable of 

 decomposing and evolving unwholesome gases. Indeed, not 

 only are the stones covered with such vegetable growths, but 

 everything in the bed of the river, such as arrested portions 

 of trees, become thickly coated. They are also seen in the 

 sewers called the Lochrin Burn sewer, the Broughton Burn, 

 and the Bull's Stank sewer at Lovers' Loan as it leaves Edin- 

 burgh, in all of which the bottom and sides are more or less 

 covered with the growths. Even in the narrowed part of 

 the channel of the Water of Leith, where the run of water 

 is great, these organic matters are abundant, and likewise 

 in the bottom and sides of the lade which traverses Edin- 

 burgh. All the twigs and branches of trees which hang 

 down into the Lochrin Burn sewer, and into the water of 

 the lade, as from the gardens behind Anslie Place and Moray 

 Place, have these growths adhering in long streamers, ren- 

 dered bulky and doubly foul by the accumulation of entangled 

 filth. These growths principally consist of those low forms 

 of vegetable life which are regarded by some naturalists as 

 Fwigi, and by others as Algce, and they are accompanied by 

 masses of animals belonging to the family of Vorticellidce, 

 including the genera Vorticella, Carchesium, Zoothamnium, 

 and Epistylis. Much of the organic matters which are found 

 entangled in the branches of trees hanging into the lath s 

 and open sewers, as also of the organic deposits which arc 

 found in the beds of the Water of Leith and of the lades, are 

 composed of the decaying remains of such growths. 



