4 GLIMPSES OF NATURE. 



each set of plumes is withdrawn, while the trap-doors 

 of the shell are closed with something which reminds 

 you of a defiant snap. This observation, then, proves 

 to us that the acorn possesses means for maintaining 

 relations with the outer world or, in plain language, 

 that it includes a nervous system among its personal 

 belongings. If you could dissect the body com- 

 pletely, you would find comprised within the shell a 

 perfect digestive system for the assimilation of food. 

 We cannot presume to gauge perfection of organs by 

 the standard of size in the world of life, and the sea- 

 acorn race illustrates this contention in an apt fashion. 

 Nor can you argue that simplicity of structure always 

 means lowness of origin, for the history of how your 

 sea-acorn came to be what it is, proves the necessity 

 for our looking backward as well as forward in the 

 matter of living histories. 



Sea-acorns are in reality poor relations of the 

 barnacles which you have seen coating the sides of 

 ships in the graving-dock. The barnacle possesses 

 a stalk, while the acorns want that appendage; and 

 therein lies the principal difference betwixt the races. 

 But both acorn and barnacle in turn show relation- 

 ships to other and widely different animals. That 

 crab which you see perambulating in the pool in his 

 own lop-sided fashion is an aristocrat of the barnacle 

 class. So also is the lobster, and the shrimp, and 

 the other shelled animals with legs. How do I know 

 this ? you inquire. Listen, and you shall be more 

 than satisfied with the correctness of my statement. 



The sea-acorn in due season develops eggs, and 

 these are liberated from the parent-shell and sent 

 forth into the world of waters to start life on their 

 own account. Each egg develops at first into a 



