LECTURE XII. 



THE PHYSICAL BASIS OF HEREDITY. 

 Prof. Frank M. McFarland. 



I, Heredity. The law of persistence in a series of 

 organisms. Like produces like. 



77. The Cell. The physical basis of life. 



1. Its structure. (^4) Protoplasm. (a) Spongio- 

 plasm ; (b) Hyaloplasm. (B) Nucleus. (a) Chro- 

 matin ; (c) Achromatin ; (d) Nuclear membrane. 



2. Protoplasm a morphological, not a chemical con- 

 ception. Its complexity. 



8. Its fundamental phenomena. Assimilation and 

 metabolism. Growth, irritability, contractility, re- 

 production. 



4. Cell multiplication. "Oninis cellula emcellula" 

 changed to " Omnis nucleus e nucleo." The spindle, 

 attraction spheres, and centrosomes exist for the 

 purpose of dividing the chromatin, the probable 

 vehicle of heredity between the two daughter cells. 



///. Multiplication Among Protozoa. Macronuclei 

 and micronuclei. Fission and conjugation. Amphi- 

 mixis. 



IV. Multiplication Among Metazoa. Histological 

 differentiation into body or somatic, and reproductive 

 cells. The origin of sex. 



1. The reproductive cells. Ova and spermatozoa. 



