ipii] William J. Gies 45 



In this introductory phase of the course to which I am alluding, 

 the composition and constituents of typical cellular masses (proto- 

 plasm) are studied; the leading cellular constituents are isolated 

 and their structural as well as their dynamic relationships are in- 

 dicated, so far as that is possible. This portion of the course is 

 also intended to establish general principles regarding the origin 

 and chemical nature of cellular constituents, the functions of cellu- 

 lar Compounds, and the processes that characterize cellular activity 

 and power. Both botanical and zoölogical materials are studied 

 experimentally in these connections. 



We then raise the question: How do animal cells obtain the 

 materials required for their " repairs " and for the replacement 

 of the substances consumed and removed in the life-giving trans- 

 formations, i. e., how are the cells nourished? The answer is 

 found, in part, in an intimate study of the physical and chemical 

 properties of lymph and blood, which are the essential and active 

 intermediaries in the exchange of materials in the animal organism 

 (metabolism). "The circulatoiy System is the commissariat of 

 the physiological army." The mechanico-chemical processes, by 

 which cells obtain (assimilate) and blood and lymph yield nutrient 

 materials, are considered both from theoretical and practical stand- 

 points. The mechanical and chemical relationships between the 

 cells and the blood, lymph, and " tissue Juices " in general, are em- 

 phasized. We show that in the exercise of their local absorptive, 

 digestive, transformative and constructive processes, the tissue 

 cells obtain from blood and lymph the materials that are utilized 

 directly or indirectly for the maintenance of cellular structure and 

 the continuance of cellular activities. 



Having established the direct nutritional dependence of animal 

 cells upon constituents of the blood and lymph, we lead the Student 

 into a study of the substances and processes involved in the renewal 

 of such constituents of blood and lymph as are utilized (assimi- 

 lated) by the cells. This inquiry is, in effect: How is the supply 

 of nutrients for the cells maintained in the blood and lymph? The 

 Chief subjects for consideration in this connection are internal and 

 external respiration, and alimentation and absorption. The oxida- 

 tive processes and gaseous exchanges involved in respiration are 



