TRANSACTIONS OF SECTIOX K. 855 



Some curious cases of travelling films, the lobes and contorted tresses of which 

 move like amoebae over the surface of the gelatine, were also examined. 



The facts point to (1) differences in colonies even of one species may depend on 

 much more subtle differences in cultures than are usually recognised ; (2) varietal 

 differences may occur in two bacilli of the same species (isolated from a river),' duo 

 to the different vicissitudes the two individuals have been subjected to during their 

 sojourn in the water ; (3) the diihculties met with in diagnosing ' species ' of 

 bacteria with the aid of works of known authority are partly due to varieties of 

 the same species being recorded by different observers under different names, and 

 the author thinks some more consistent prearranged plan of working out the 

 characters of such forms should be developed by bacteriologists than at present 

 exists. 



3. On a Supposed Case of Symbiosis in Tetraplodon. 

 £y Professor F. E. Weiss. 



The author exhibited specimens of Tetraplodon from the CachuUin Hills in 

 Skye, where it was found plentifully on animal excreta. In September he found 

 many of the patches mixed with an orange-coloured Peziza, which did not appear 

 to have in any way injured the moss plants. The rhizoids of the moss, however, 

 contained in many cases fungal hyphse closely resembling those of the Peziza, and 

 though present in the cells of the moss these latter did not seem to be injured by 

 them. Pie suggested that this might be a case of symbiosis ; the moss, as in the 

 case of other green plants, making use of the fungal hyphse to obtain its nutriment 

 from the organic material. The ultimate proof of such a case of symbiosis would, 

 however, necessarily depend upon culture experiments, which he xmderstood were 

 now being made by another observer. 



TUESDAY, SEPTEMBER 17. 



The following Papers were read : — 



1. On Amber. By Dr. Conwentz, Danzig. 



The author of this paper gave an account of the Baltic and English amber, and 

 their vegetable contents. After describing the different forms of Tertiary amber, 

 be referred to the occurrence of succinite on the coasts of Essex, Suffolk, and Nor- 

 folk ; the specimens are usually found with seaweed, thrown up by the tides. 

 Occasionally pieces have been met with weighing over two pounds. Dr. Conwentz 

 described the method of examining the plant fragments enclosed in amber, and 

 compared the manner of preservation witli that of recent plant sections mounted in 

 Canada balsam. The amber was originally poured out from the roots, stems, and 

 branches of injured or broken trees, in the form of resin, which on evaporation be- 

 came thickened, and finally assumed the form of succinite or some similar sub- 

 stance. For the most part the fossil resin was derived from the stems and roots of 

 coniferous trees of the genus Pinus. In addition to the exceptionally well-preserved 

 tissues of coniferous trees, the Baltic amber has yielded remarkable specimens of 

 monocotyledonous and dicotyledonous flowers. Some of the most striking examples 

 were illustrated by means of the excellent coloured plates from Dr. Conwentz's 

 monograph on the Baltic amber.' 



' Monographic der haltischen Berratebibdumc. Danzig, 1 890 



