314 (hi the Erratic* of the Alps. 



for the threefold operation — of detaching the fragments small and 

 great from the parent rock by the slow action of the elements — 

 enabling them to perform such long journeys — and redistributing 

 them over so wide a space. 



Traces have been found of the former existence of glaciers in Mount 

 Jura, in the Vosges, in Wales, Scotland, Norway, and Sweden ; and 

 there is no reason to doubt that the glacial period in all these 

 countries was coincident with that of the great ancient extension of 

 glaciers in Switzerland. The aspect during that long period, of all 

 Europe northward of the Alps, or perhaps the Pyrenees, must have 

 resembled that of Sweden in the gloomy months of winter. The 

 genial powers of nature lay benumbed under a perpetual winding- 

 sheet of snow and ice, covering mountain and valley, spreading death 

 and hopeless sterility over the whole north, and the plains of Britain, 

 France, and Germany, where flocks and herds now pasture, and rich 

 harvests bloom, and mighty cities teem with millions of industrious 

 men living in security and comfort. 



The question remains, " What length of time separates the glacial 

 period from that in which we live ?'' To this question no definite 

 answer can be given, but it may be safely said that the glacial period 

 had passed away long before the appearance of Man upon the earth. 



to imti ; oonnoD oaofo oa ctfni {frirguoid 



1 iii Mworis— -jshoeiflcrl 



9lni odi — /roifto 9ift to noiiibnoo Lev 

 Infusoria, the earliest Larval state of Intestinal Worms, 

 according to Professor Agassiz. 



Although for want of time, says Agassiz, in a letter to 

 Mr Dana, my investigations on intestinal worms have been 

 limited, I have arrived at one important result. You may 

 remember a paper I read at the meeting at Cambridge 

 (America), in August 1849, in which I shewed that the em- 

 bryo which is hatched from the egg of a Planaria, is a 

 genuine polygastric animalcule of the genius Paramecium, 

 as now characterised by Ehrenberg. In Steen strap's work 

 on alternate generation, you find that in the extraordinary 

 succession of alternate generations ending with the produc- 

 tion of Cerceria, and its metamorphosis into Distoma, a 

 link was wanting, — the knowledge of the young hatched from 

 the egg of Distoma. The deficiency I can now fill. It is 

 another infusorium, a genuine Opalina. With such facts 

 before us, there is no longer any doubt left respecting the 

 character of all these Polygastrica ; they are the earliest 



