EXPLANATION OF PLATES. 

 PLATE 1. 



1. Photograph of the membrane of connective tissue of 48-hour growth from a tissue culture of a piece of stomach of 



a 6-day chick embryo. 4 oc. and 4 mm. lens. Zeiss. 



2. Photograph of cells and fibers in a film preparation of subcutaneous tissue of an 18-day chick embryo. Os. yap., 



iron hem. 4 oc. oil-imm. lens. 



3. Camera-lueida drawing of a living cell from a culture of subcutaneous tissue of 14-day chick embryo, 3-hour 



growth. 6 oc. 4 mm. lens. 



4. 5. Camera-lueida drawings of living cells in a hanging-drop preparation, after Bell, of subcutaneous tissue from a 



14-day chick embryo in Locke's solution. 4 oc. 4 mm. lens. 



6. Retouched photograph of 48-hour growth from arachnoid tissue of 7-day chick embiyo. Oi-. vapor, hon hem., 



4 oc. oil-imm. lens. 



7. Photograph of 48-hour growth from leg of 8-day chick embryo. Os. vap., iron hem., and eosin. 4 oc. 4 mm. lens. 



8. Photograph of 48-hour growth from subcutaneous tissue of 10-day chick embryo. Os. vap., iron hem. 6oc. 4 mm. 



lens. 



9. Photograph of 48-hour growth from heart of 7-day chick embryo. Os. vap., iron hem. 4 oc. oil-imm. lens. 



PLATE 2. 



1. Camera-lueida drawing of cell, showing primitive fibrils in the cytoplasm. 48-hour growth from subcutaneous 



tissue of 9-day chick embryo. Os. vap., iron hem., and eosin. 4 oc. oil-imm. lens. Drawn by Miss J. E. 

 Lovett. 



2. Camera-lueida drawing of cells and fibrils united into bundles. 72-hour growth from subcutaneous tissue of 



1 1-day chick embryo. Os. vap., iron hem., and eosin. 4 oc. oil-imm. lens. Drawn by Miss J. E. Lovett. 



3. Camera-lueida drawing showing cells with fibrils within the cytoplasm and also fibers. 120-hour growth from 



subcutaneous tissue of 11-day chick embryo. Os. vap, iron hem., and eosin. 4 oc. oil-imm. lens. Drawn 

 by Miss J. E. Lovett. 



4. Camera-lueida drawing of cells from 24-hour growth of leg of 8-day chick embryo. Os. vap., iron hem., and eosin. 



4 oe. oil-imm. lens. 



5. Camera-lueida drawing of cell undergoing mitosis in 48-hour growth from subcutaneous tissue of 11-day chick 



embryo. Os. vap., iron hem., and eosin. 4 oe. oil-imm. lens 



6. Camera-lueida drawing of smooth muscle-cells, showing myofibrils from 48-hour growth of amnion of .5-day chick 



embryo. Os. vap., iron hem. 4 oc. oil-imm. lens. 



7. Camera-lueida drawing of cell from 24-hour growth of 6-day chick embryo, showing deposit along surf ace of the cell, 



which is stained like mitochondria with Bensley's aniline fuchsin, methylene green stain. 4 oc. oil-imm. lens. 



8. Camera-lueida drawing of tendon-cells from 72-hour growth of muscle of 9-day chick embryo. Zenker's fixation 



Mallory's stain. 4 oc. oil-imm. lens. 



9. Camera-lueida drawing of epithelial cells of 48-hour growth from amnion of 5-day chick embryo. Iodine-vapor 



fixation Mallory's stain. 4 oc. oil-imm. lens. 



10. Camera-lueida drawing of thin membrane of connective tissue from 72-hour growth of 10-day chick embryo. 

 Silver nitrate and Ehrlich hematoxylin. 4 oc. and oil-imm. lens. 



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