NATURAL HI3TOHY. 37 



" Man marks not thee, marks not the mighty hand 

 That, ever busy, wheels the silc-ut spheres; 

 Works in the secret deep." THOMSON. 



the same amount and quality of food would overtax the powers 

 and functions of the infant. 



103. If a small drop of milk be submitted to the microscope it will be found to 

 manifest nearly the same appearances as a drop of blood will present. A multitude 

 of minute pearly sphericles with the most perfect outline, reflecting light brilliantly 

 from their centre, and varying in magnitude from the 12,500th to the 3,000th part 

 of an inch in diameter, and even larger as seen floating in the fluid. The general 

 magnitude and number of these globules vary much, not only in the case of one 

 species of animal compared with another, but with different individuals ol the same 

 species, and even with the same individual under different circumstances. The 

 constituent upon which the nutritive properties of milk mainly depends is butter ; 

 in this respect woman's milk is found to be by far the richest, as will be seen from 

 the following comparative results : 



Woman. Cow. Goat. Ass. 



Butter 8-97 2-68 4-56 1-29 



Sugar of Milk 1-20 5-68 9-12 6-29 



Cheesy Matter 1-93 8-95 4'38 1'95 



Water ... .. 87-90 .. .. 82'69 .. .. 81-94 .. .. 90-47 



100-00 100-00 100-00 100-00 



104. Why is it better for mankind that the action of the L^^ 

 organs of the body are hidden from sight ? 



Because were we sensible of the organic motions di 'L ve 

 when the heart beats, the lungs play, and the stoi'iv,'j 

 the consciousness could not promote, but might di'j'Aib the due 

 and orderly course of these processes. 



105. We do not know when the heart dilates to receive the ^ Ol cutrent, nor when 

 it contracts to propel it with renewed impetus through the jj r iMa ; nor when the 

 blood rushes to the lungs to give out its useless and noxious y Jt'jlw ; nor when the 

 air rushes to the blood to take up those particles, to rer L*ff '.roar; by others, and 

 thus to purify and renovate the vital fluid. Many prov* jC rf this kind are con- 

 tinually going on within us during every moment of ru.- ei's'ence, but we are no 

 more conscious of them than we are of the motion of tflt folds in the blade of grass 

 on which we tread. On the contrary, when an jx.tjrral object produces in a 

 sentient nerve that change of state which we denot j "jy the words " an impression ;" 

 when the sentient nerve transmits this impress '.CA to the brain ; when the brain 

 is thereby brought into the state of perception , f AU animal life is in active operation, 

 and percepient or conscious existence tatr , p\ace. 



