15 

 16 



17 



20 



27 



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29 



30 



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12 



19 



21 



22 





23 



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24 



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25 



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28 



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31 



14 



13. Photomicrograph o( macrophages in cavum mediale. X 1000. 



14. Photomicrograph of chorionic villus of Embryo 350. X 410. 

 15-17. Macrophages from the chorionic villi. X 1000. 



18-30. Macrophages from the cava corporis striati. X 1000. 



31. Normal erythrocytes from a 15 mm. human embryo. X 1000. 



