PLATE 5 



EXPLANATION OF FIGURES 



32 to 45 Cytoplasmic constriction in living vessels. Cytological characteris- 

 tics and degenerative changes in cultures. 



32 and 33 Erythroblasts as observed within the living vessels in the foetal 

 membranes of a 22 mm. embryo, immediately after the removal from the uterus. 

 Shows cytoplasmic constriction and origin of a non-nucleated element in a manner 

 comparable to the process observed in the cultures (figs. 13-18). Neighboring ery- 

 throcytes in the vessel not drawn. 



34 Experiment 4; twenty-five-hour autoplastic culture, + Ringer's solution, of 

 the blood from a 25 mm. embryo. Shows the origin and behavior of vacuoles, 

 presumably degenerative in character. At stage /' the original vacuole has become 

 divided into two parts. 



35 Experiment 52; migratory movements of a small vacuole in the cytoplasm 

 of an erythroblast; sixty-nine-hour autoplastic culture of blood from a 33 mm. 

 embryo. 



36 Amoeboid-like changes in the cytoplasm of an erythroblast as observed 

 in the living blood vessels in the foetal membranes of a 28 mm. embryo immediately 

 after the removal from the uterus. 



37 to 40 Vacuoles in the cytoplasm of erythrocytes showing a tendency to 

 collect around the nucleus in the erythroblast (figs. 38-39) and at the periphery of 

 a plastid (fig. 40). Experiment 54; twenty-hour autoplastic culture from a 25 mm. 

 embryo. 



41 Erythroblast in fresh blood just taken from the heart of a 27 mm. embryo, 

 showing a thickening of the cytoplasmic rim of the disc in the region of the nucleus. 



42 Experiment 51; twenty-one-hour autoplastic culture from the blood of a 

 30 mm. embryo. Erythroblast in telophase of mitosis, the daughter cells being 

 still connected by a thread of cytoplasm (compare with figure 7). 



43 and 44 Cup-shaped erythroblasts; Experiment 55; two-day autoplastic cul- 

 ture from the blood of a 31 mm. embryo. 



45 Experiment 52; four-day autoplastic culture from the blood of a 33 mm. em- 

 bryo. Two aspects of an erythroblast, in the profile view b of which, the nucleus 

 presents the deceptive appearance of a nuclear extrusion. 



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