62 NATURAL HISTORY 



The space between the diaphanous globules is generally 

 filled with minute green particles : it moves but seldom, 

 and appears at first indifferent which end shall proceed 

 foremost. They are eaten by the Proteus diffluens and 

 the large Vorticella, which see. 



The oat animal described by Baker is probably only a 

 variety of the two preceding species, and as he seems 

 to have examined them more accurately than Muller, I 

 shall append his account of them for the information of 

 the reader. 



" This creature is so very small that no true judgment 

 can be made of itunless it be looked at through the greatest 

 magnifier, nor even then without considerable attention. 

 I commonly found tw^o or three of them in a drop of 

 the sediment, amongst multitudes of the hair- like- insect, 

 Iving at the bottom of the water wherewith the sedi- 

 ment was diluted upon the stage-glass, without any visi- 

 ble motion or appearance of life. They are inclosed in 

 a bivalve shell, which the animal can open or shut at 

 pleasure, but which it constantly shuts upon being dis- 

 turbed, nor opens again until after having been quiet 

 for some time. 



" The shell is so exquisitely thin, and consequently so 

 very transparent, as to be traced out, when shut, only by 

 a faint line on the back, where the cardo or hinge makes 

 some additional thickness ; but when open, the edges of 

 both its sides may be plainly distinguished. The two 

 ends of the shell can open whilst the middle part remains 

 closed, and in that condition it is like the Pholas, and 



