160 physiological regulations 



§ 62. Cells and nuclei 



It would be a pleasure to include in the present study changes 

 in the volumes of cells within animals. Possibly recoveries of 

 volume are ascertainable in circulating erythrocytes {in situ), but 

 they have not been ascertained. Some sort of opacitometer plus 

 enumerator is required to play upon the blood within the blood 

 vessels, calibrated specifically for volume changes. Increments of 

 volume found in drawn blood have probably occurred much more 

 quickly than subsequent measurements can be made. 



In some tissues, areas of single cells (Hirsch, '37) and nuclei 

 (Wermel and Portugalow, '35) may be directly measured. The 

 water exchanges might then be ascertained immediately after the 

 microinjection of fluid into or the emptying of material from those 

 units. Eventually other subdivisions of single cells and of unicellu- 

 lar organisms may be similarly observed. The rates of shrinking 

 or swelling in nucleoli, granules, and other units recovering from 

 various disturbances of volume (preferably those that affect the 

 unit more than the remainder), may then be measured, and the 

 equilibration of volume described. 



At present this measurement has proven feasible upon the 

 germinal vesicles in ova of invertebrates. In a species each of 

 echinoderm and of annelid eggs, volume changes during swelling 

 of the germinal vesicles (nuclei) are measured in parallel to those 

 of the whole individual {Asterias, Beck and Shapiro, '36; Cerato- 

 cephale, Kamada, '36; Arhacia, Churney, '41). The interval of 

 time between swelling of the Qgg and swelling of the nucleus is much 

 shorter for the echinoderm eggs in sea water than for the worm 

 eggs immersed in a modified Ringer's solution, although the time 

 required to complete the swelling is about the same in all species. 

 Possibly similar contrasts would occur during recoveries from 

 water loads ; at least the measurements have been demonstrated to 

 be feasible. 



§ 63. Summary of parts in situ 



The studies of recoveries of volume in situ mostly concern 

 volumes of distribution as measured by adding or subtracting 

 components in the body. In one study, "plasma" and ''blood" 

 volumes of rabbits are reduced by hemorrhage and augmented by 

 transfusion. Thereupon exchanges appear that effect restorations 

 of volume; "plasma" volumes recover much more quickly than 



