IN MEDICAL SCIENCE. 33 



scopist, as the bull's-eye in the old-fashioned window- 

 pane. Everywhere we find cells, modified or un- 

 changed. They roll in inconceivable multitudes (five 

 millions and more to the cubic millimetre, according 

 to Vierordt*) as blood-disks through our vessels. A 

 close-fitting mail of flattened cells coats our surface 

 with a panoply of imbricated scales, (more than twelve 

 thousand millions, as Harting has computed,*}") as true 

 a defence against our enemies as the buckler of the 

 armadillo or the carapace of the tortoise against theirs. 

 The same httle protecting organs pave all the great 

 highways of the interior system. Cells, again, preside 

 over the chemical processes which elaborate the hving 

 fluids ; they change their form to become the agents of 

 voluntary and involuntary motion ; the soul itself sits 

 on a throne of nucleated cells, and flashes its mandates 

 through skeins of glassy filaments which once were 

 simple chains of vesicles. And, as if to reduce the 

 problem of living force to its simplest expression, we 

 see the yolk of a transparent egg dividing itself in whole 

 or in part, and again dividing and subdividing, until it 

 becomes a mass of cells, out of which the harmonious 

 diversity of the organs arranges itself, worm or man, as 

 God has willed from the beginning. 



This differentiation having been effected, each sev- 

 eral part assumes its special office, having a life of its 

 own, adjusted to that of other parts and the whole. 



* KoUiker, Manual, etc., (London, I860,) p. 518. 

 t Valentin's Physiology, (Brinton's Transl.,) p. 13. 



2* c 



