1 62 A HANDBOOK FOR SOUTHPORT. 



species, as assemblages of individuals, marked out from each 

 other by definite characters, that have been generically trans- 

 mitted from original prototypes, similarly distinguished, is 

 quite inapplicable to this group, since, even if the limits of 

 such assemblages were extended so as to include what would 

 elsewhere be accounted genera, they would still be found so 

 intimately connected by gradational links that definite lines 

 could not be drawn between them." He also propounds the 

 idea that the many generic and specific forms may be traced 

 up to a very few original and leading types, which have multi- 

 plied by diversities of temperature, depth, geological position, 

 and local influences, thus exhibiting in this group, to a certain 

 extent, Mr. Darwin's theory of multiplication of species by 

 natural selection. This theory receives a certain amount of 

 confirmation when we notice the comparatively few species 

 found in the profound depths of the ocean, where the disturb- 

 ing influences are small ; and the great number of apparent 

 species and varieties found in shallower waters, where disturb- 

 ing influences of every kind are constantly in operation. 



The propagation and development of the Rhizopods are not 

 yet definitely defined. Further observations of the living 

 animal are required before we can read their life-history with 

 certainty ; the information we possess leads to the inference 

 that they are propagated by fission. The Amoeba has been 

 observed to throw out a pseudopod, a little thickened at the 

 end, and attach it to an object ; then, without drawing the 

 body forward, the filament has gradually become thinner until 

 the enlarged point has become detached, and like the original 

 body, has thrown out pseudopodia of its own. Similar phe- 

 nomena have been observed in the Foraminifera, or the shell- 



