HO THE MICROSCOPE. 



power of 400 or 500 diameters, you will notice a great 

 quantity of rounded flattened bodies. Ehrenberg, I 

 believe, was the first person to observe and describe 

 these little particles. Formerly these bodies were sup- 

 posed to be mineral concretions of particles derived 

 from organic bodies. They were called crystalloids, 

 and are thus described in the " Micrographic Dic- 

 tionary," under the word chalk: "The cementing 

 material of chalk consists of very minute, numerous, 

 and remarkable bodies, called crystalloids; they are 

 elliptical, or rounded and flattened, from TOO^O to 

 a-gVo in length, the most numerous perhaps -^Q-Q. 

 Some of them consist of a simple ring ; in others it is 

 marked with pretty regular transverse lines, so as to 

 make it appear jointed; in others, again, there is a 

 thinner central portion, often exhibiting one or more 

 granules. M. Ehrenberg regards these as arising from 

 the disintegration of the microscopic organism forming 

 the chalk into much more minute calcareous particles, 

 and their reunion into regular elliptical plates (or 

 discs) by a peculiar process, differing essentially from 

 and coarser than that of crystallisation, but com- 

 parable with it ; one probably preceding all slow crys- 

 talline formation, and causing, but not alone, the 

 granular state of solid inorganic matter." Recent 

 investigations, however, afforded by the mud, or ooze, 

 obtained from the deep sea, have been supposed by 

 some to confirm the opinion, first, I believe, made 

 public by the Rev. J. B. Reade, that these so-called 

 crystalloids are organic. They are now known by 

 the name of coccoliths and coccospheres, and have 

 been found abundantly in the sticky mud of the 

 Atlantic sea-bed. These bodies, be they animal or 

 vegetable, are of extreme low organisation, and are 

 not confined to deep water, for Dr. Wallich has ob- 

 tained them off the coast of Plymouth at about seven- 



