104 LABORATORY MANUAL OF GENERAL PHYSIOLOGY 



CO2 dissociation curve. Seal the outflow tube with mercury after admit- 

 ting the final portion of the gas. Determine the O2 content. Determine 

 the oxygen capacity of the blood used, and estimate the percentage 

 saturation of each sample, as follows : 



Content 

 The percentage saturation = ^ • X 100 



Plot the percentage saturation as ordindtes against the O2 pressure and 

 draw a curve from the origin through the points. Cf. Henderson, 

 "Blood," p. 75; Bayliss, p. 621. Text p. 414. 



6. Determination of the O2 Capacity of Limulus Blood. — Read Red- 

 field's paper (J. Biol. Chem., 69: 475, 1926) before attempting experiment. 

 Blood may be drawn from the cephalothorax by inserting a cannula. 

 A heavy agglutinum forms on standing. This can be removed by centri- 

 fuging or by shaking while agglutination is taking place and then filter- 

 ing off the serum. 



The following modifications of standard procedure are necessary. 



Trap the fluid after extraction of the gas (to prevent trouble from 

 agglutinum). Estimate correction for added reagents by measuring at each 

 reading the height of the column of aqueous fluid in the burette (use the 

 attached min. scale from 0.5 cc. mark downward). Multiply the differ- 

 ence in the height of the water column by 0.926 (gives pressure due to the 

 Hg displaced less the fraction of this pressure due to the displacing water). 



Decolorize the oxyhaemocyanin by introducing 5% KCN saturated 

 with caprylic alcohol into the burette and remove dissolved gases. Run 

 the sample into this solution. A fine white precipitate is produced from 

 the haemocyanin which gives up its O2 uniformly. Sodium hydrosulfite 

 and IN NaOH are used for reabsorbtion of CO2 and O2. 



Plot the percentage saturation as ordinates against the O2 pressures and 

 draw a curve from the origin through the points. Compare with the 

 haemoglobin curve. Cf. Henderson, "Blood," Fig. 208, p. 322. The 

 chemical nature of haemocyanin is discussed in Harrow and Sherwin's 

 "Biochemistry," pp. 504, 529, 1935- Text p. 416. 



XVI. COMPARATIVE PHYSIOLOGY OF RESPIRATION 



1. Human Respiratory Movements. — With chest in mid-way position, 

 fasten the Fitz pneumograph by means of the chain. Cautiously connect 

 tube to tambour and record normal respiratory movements (eupnea) 

 on a kymograph drum (time marker, 5 sees). Record (a) the effect of 

 breathing through a narrow tube (dyspnea); (b) forced breathing, (c) 

 swallowing, (d) singing, (e) reading aloud, (f) sneezing (sniff pepper, 

 snuff or cigarette smoke), (g) coughing, (h) hiccoughing, (i) belching. 



