Geological Society. 481 



larity. It seems the cultivated Schizophytes change and de- 

 velop more slowly, and probably on that account are less vigo- 

 rous in producing mischief; at any rate, an inoculation with 

 cultivated Swine-plague Schizophytes, although effective in 

 producing the disease, is always followed by a comparatively 

 milder form of Swine-plague than an inoculation with material 

 directly from the body of a diseased hog.j^ This, however, does 

 not involve that every inoculation with cultivated Schizo- 

 phytes produces under all circumstances a milder form of 

 Swine-plague tlian any natural infection ; for such is not the 

 case. The difference may be stated thus : — A natural infec- 

 tion, or an inoculation with material directly from the body 

 of a diseased hog, as a rule, produces a malignant and dange- 

 rous attack, and as an exception a mild form of the disease — 

 the frequency of the exception depending, it seems, to a great 

 extent, upon the prevailing character of the plague ; while an 

 inoculation with the cultivated Schizo]:iliyte is, as a rule, 

 followed by a mild attack, and, as an exception, or in rare 

 cases only, by Swine-plague in its severest form. 



Wherever Swine-plague is prevailing in its most malignant 

 or fatal form, or, what is essentially the same, wherever for- 

 mation of ulcerous tumours in the ceecum and colon is afrequent 

 occurrence, where consequently an abundance of Swine-plague 

 Schizophytes is discharged with the excrements of the dis- 

 eased animals, there the spreading from animal to animal, and 

 from herd to herd, is a rapid one ; and vice versa, wherever 

 the spreading is rapid, there ulcerous tumours in the intestines 

 are a frequent occurrence. In 1878 the same (the ulcerous 

 tumours) could be found in about 75 per cent, of all cases that 

 had a fatal termination, while at present (in Illinois) their 

 occurrence is probably limited to about 5 per cent, of all 

 cases. 



PROCEEDINGS OF LEARNED SOCIETIES. 



GEOLOGICAL SOCIETY. 



February 23, 1881.— Robert Etheridge, Esq., F.R.S., 

 President, in the Cliair. 



The following communication was read : — 



" On Astroconia Granti, a new Lyssakiue Hexactinellid from 

 the Silurian Formation of Canada." By Prof. W. J. SoUas, M.A., 

 F.G.S. 



This paper contained a description of a new fossil HexactineUid 

 sponge from the Niagara chert beds of Hamilton, Ontario. It is 



