692 REPORT—1899. 
roadways, and from the wear of the wooden paving-blocks of the streets. If the 
sandy detritus brought down by the sewage in storm weather is allowed to settle: 
before the sewage flows upon the coke-beds, a second process of sedimentation 
removes the larger amount of cellulose matter, and of this latter sediment about 
70 per cent. is combustible when the matter has been dried. 
Hence it appears possible to carry on the solid feecal matter to the coke-bed, 
and to deal with the sand and cellulose matters by sedimentation, the latter being 
subsequently disposed of by combustion. 
The comparative bacteriological study of the raw sewage and of the effluent by 
Dr. Houston shows that practically no bacterial improvement is brought about by 
the treatment of the sewage in the coke-bed. The presence of bacteria in the 
effluent is, however, advantageous in securing its final purification. 
The effluent has supported the life of fish, which were immersed in it, for 
several months. Their health suffered no appreciable deterioration; apparently 
they could live in it indefinitely. 
That the coke-beds become fully aérated by the intermittent treatment is 
evident from the fact that after 70 hours’ rest in an empty condition the air at the 
bottom of the 15-foot bed contained 14:7 per cent. of oxygen and only 0'8 per cent.. 
of carbon dioxide. 
1l. On the Place of Nitrates in the Biolysis of Sewage. 
By W. Scorr-Moncrierr. 
SATURDAY, SEPTEMBER 16. 
Joint Meeting with Section K. 
The following Papers were read :— 
1. The Excretory Products of Plants. By Professor Hanrior:. 
2. A Discussion on Symbiotic Fermentation, opened by the reading 
of the following papers :— 
Symbiosis. By Professor Marsuatt Warp, /.2.S. 
Synopsis. 
Origin of the idea and of the term. Differences between parasitism and’ 
symbiosis. 
Lichens, previously regarded as autonomous plants, are shown to be dual 
organisms, a symbiosis of alga and fungus. Controversy regarding the lichen 
theory, and establishment of the latter by means of synthetic cultures. 
Other cases of symbiosis known previous to 1880. Algz in the stems of 
Gunnera and the roots of Cycas, in the thallus or fronds of Anthoceras and 
Blasia, Azolla, Lemna, &e. 
Extension of the idea of symbiosis : insect fertilisation, epiphytes, &c. 
Galls not necessarily due to insects, but may be due to the irritating action of 
fungi or bacteria. Phytocecidia of the Aleppo pine, &c. 
Symbiosis in animals, Green infusoria, hydra, sponges, &c. 
Mycorhiza, the roots of many humus plants curiously swollen and modified 
owing to the presence of fungi, which do not injure the plant, but link its roots to: 
the decomposing leaves around. Explanation as an instance of symbiosis. Evidence 
partly anatomical and partly experimental. 
