194 Objects for the Microscope. 



CHAPTER X. 



FOBAMINATED SHELLS. 



I BELIEVE that every one is surprised and delighted with 

 these lovely little shells ; so minute that they resemble 

 grains of the finest sand ; and so perfect in structure that 

 they seem to be the habitation of a more highly organized 

 animal than they really are. 



There are two kinds of foraminated shells, calcareous 

 and siliceous. The calcareous shells are found alive in 

 marine deposit, and on sea-weed ; the siliceous are also 

 dredged up from the depths of the sea, and found in strata 

 formed of fossil deposits. 



The animals which dwell in these beautiful little shells 

 are of the lowest order in the scale of animal creation, not 

 yet perfectly understood, and are variously placed by 

 scientific men. Formerly they were considered as belong- 

 ing to the family of Cephalopods, or Cuttle-fish. Ehren- 

 berg, a great naturalist, regarded them as polypes, and 

 placed them amongst the Bryozoa, or Zoophytes. Du 

 Jardin, a French naturalist, and most modern authors, agree 

 in the relationship of foraminifera to those very curious 

 animals, Amoeba and Actinophrys sol, which are found in 

 fresh water, and may be studied from our aquariums. 



Their internal organization is a simple body of what is 

 called sarcode, a kind of pulp which has the power of 

 assimilating and digesting food in all its parts. The body 

 has no particular mouth, stomach, or intestine, neither has 

 it eyes or other senses, except feeling ; but it can put- 

 forth long feelers through the perforations in the shell, 

 and can entangle and draw in its appointed food, which, 

 whenever it enters, is presently digested, and the residue 

 ejected, not always out of the shell, for the cavities are 

 sometimes choked up by these undigested atoms. 



Now in some of the Eoraminifera the body is single and 



