616 ECOLOGY AND BEHAVIOR 



Table 2. Alterations in diameter of nuclei in cells of the rectal gland. 



Results of Tukey test for significant difference at 0.05 level. (Those underlined are not 

 significantly different.) 



Figures 2 and 3 present the alterations in the histological character of the 

 gland of experimental animals. The vascularity of the glands of animals 

 sacrificed while still active was invariably greater than in control animals, and 

 the nuclei of the parenchymal cells were enlarged (Table 3). As the condition 

 of the animal worsened, the height of the glandular cells decreased, and they 

 became cuboidal in form. These cells appeared to posses a homogeneous 

 cytoplasm, and contained little demonstrable lipid. Nuclei became smaller 

 and more densely stained, and shifted towards a central or apical position. 

 The cholesterol content of the gland decreased markedly (Table 4). The 

 interrenals of animals sampled immediately after death in the pen or sacri- 

 ficed when death appeared imminent (indicated by immobility and low 

 hematocrit values) were greatly altered. The lipid content of the gland was 

 greatly reduced, and the cells showed little cytoplasmic vacuolation. Numer- 

 ous blood cellular elements were present, and polymorphs no longer ap- 

 peared restricted to vascular spaces. In the most extreme instances, the gland 

 was totally disorganized. Thus, the histological picture indicates activation of 

 the gland followed by gradual exhaustion of the parenchymal cells (Cain 

 1950; Long 1947; Moon 1961; Weatherley 1963). 



Changes in hematocrit values were marked over the experimental period; 

 they fell steadily from an average of 20 to percentages as low as 2-4 (see 

 Figure 4). A change in the character of the hematopoeitic organs occurred as 

 the hematocrit declined. The red pulp of the spleen contained progressively 

 fewer mature red blood cells; erythroblast and hemocytoblast mitoses be- 

 came more frequent in all hematopoeitic organs. Erythroblasts, and ulti- 

 mately hemocytoblasts, made up a significant portion of the cells of the 

 circulating blood (up to 24%, not including immature erythrocytes). Red 

 blood cells with aberrant shapes (i.e., of exceptional size, spherical or scal- 

 loped in profile) were apparent in blood vitally stained with brilliant cresyl 

 blue or new methylene blue. The polymorphs often contained a dense, 

 brownish pigment; a pigment of similar appearance was also found in the 



