Fig. 4. Number of lymphocytes (medians ±0.5 interquartile intervals) per 1000 erythrocytes counted on stained thin blood smears of adult male house finches treated with testosterone-filled (black circles; N=10) or control (white circles; N=10) Silastic capsules. Capsules were implanted on Day 0. All birds received one weekly injection of sheep red blood cells for 4 weeks starting on Day 13.