PLATE 1 



EXPLANATION OF FIGURES 



The sixteen figures are all of mesenchyme cells from the same culture. The 

 explant from the leg of a seven-day chick embryo, gave rise to an average out- 

 growth in Locke's solution plus 5 per cent dextrose. After forty-eight hours the 

 culture was washed with a solution of neutral red and janus black no. 2. The 

 mesenchyme cells contained rather few red granules. The mitochondria were 

 in the form of threads and rods. The centrospheres varied from small to fairly 

 large ones. After a brief examination, the culture was washed with one drop of 

 a 1 /40,000 solution of potassium permanganate and the usual changes were ob- 

 served in the nucleus and in the mitochondria. Sixteen minutes after the appli- 

 cation of the potassium permanganate the specimen was fixed in Zenker's fluid 

 without acetic acid, and stained with iron haematoxylin and eosin. The figures 

 were drawn with a camera lucida at a magnification of*r250 diameters with one- 

 half reduction in printing. Many of the fine processes of the cells were not car- 

 ried out to full length. 



1 Metaphase, mitochondrial vesicles (small circles), dense cytoplasmic mass. 

 X 625. 



2 Anaphase. 



3 Telophase, mitochondrial vesicles in dense cytoplasm. 



4 Daughter cells with dense cytoplasm, small mitochondrial vesicles, one 

 nuclear vacuole. 



5 Daughter cells, mitochondrial vesicles, centrospheres, nuclei each with one 

 nuclear vacuole. 



6 Older daughter cells with mitochondrial vesicles, each cell with a small 

 dense cytoplasmic area and centrosphere and each nucleus with halo of small 

 nuclear vacuoles about a small dense chromatin mass. 



7 Mesenchyme cell, small dense cytoplasmic area probably about centriole, 

 mitochondrial vesicles, nuclear vacuoles about pycnotic dense nucleus. 



8 Cell with mitochondrial vesicles, nuclear vacuoles and pycnotic nucleus, 

 but no dense cytoplasmic area or centrosphere. 



9 Cell with dense cytoplasmic area, large centrosphere, mitochondrial vesi- 

 cles, and nuclear vacuoles. 



10 Cell with mitochondrial vesicles, large centrosphere, nuclear vacuoles 

 and pycnotic nucleus. 



11 Elongated mesenchyme cell with small area of dense cytoplasm, mitochon- 

 drial vesicles, and dense nucleus. 



12 Cell with area dense cytoplasm and centrosphere in the same end of the 

 cell; mitochondrial vesicles, nuclear vacuoles, and dense pycnotic nucleus. 



13 Cell with mitochondrial vesicles and a corona of nuclear vacuoles about 

 pycnotic nucleus. 



14 Cell with large dense cytoplasmic area, mitochondrial vesicles, and corona 

 of nuclear vacuoles about pycnotic nucleus. 



15 Binucleate cell with one large centrosphere, mitochondrial vesicles of 

 various sizes, corona of nuclear vacuoles about dense nuclei. 



16 A much flattened mesenchyme cell from periphery with mitochondrial 

 vesicles. No nuclear vacuoles were formed. 



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