27 



LECTURE III. 



The Ovum, or Egg — Of Development — Interstitial Chan- 

 nels — Vessels — Structures and Organs — Alimentary 

 Canal — Glands for producing Solvent Fluids — The 

 Blood for Nutrition — The Lungs for Eespiration — 

 The Liver for making Bile and Sugar, and altering 

 the Blood — The Kid neys for forming and separating 

 Excrementitious Matter — Cutaneous Glands for Se- 

 creting — Temporary Structures for tise while the Per- 

 munent Organs are being formed — Skeleton — The 

 Nervous System — The Mtiscular System — The 

 Limhs — The Skin ivith Touch Organs — The Tongue 

 —The Nose— The Ear— TJie Eye. 



44. The Ovum or Egg. — The contents of the bird's 

 egg are not directly converted into the tissues of the 

 chick, but probablymore thannine hundred andninety- 

 nine thousandths of the egg of the bird consist of 

 pabulum upon which the developing embryo is to live. 

 These constituents of the yolk, as well as the albumen 

 or white of the egg, are taken up and changed by the 

 minute speck of bioplasm which is the germ of the 

 growing chick, jnst as food is taken up and appro- 

 priated by other forms of living bioplasm (§ 40). 

 As soon as vessels are developed, these substances 

 are taken up by bioplasm, just as pabulum from 

 the intestinal Cfinal in after liie, and converted into 

 blood. From this blood the various substances out 

 of which the tissues are formed are taken. The won- 

 derful growing point or spot which though so minute 

 is the most important part of the egg, can always be 

 seen if the egg be placed on its side and a portion of 

 the uppermost part of the shell be carefully removed. 



