462 C. C. MACKLIN. 



EXPLANATION OF PLATES. 



PLATE I. 



FIGS, i TO 12. Successive stages covering a period of 2% hours in the life history 

 of a connective tissue cell from a 57-hour culture of 5-day chick heart, growing in 

 Locke solution (0.5 per cent, dextrose with extract of chick embryo). The nucleus 

 finally divides by direct fission. Small circles represent fat globules and short 

 threads mitochondria, c. Fig. i, points to the centrosphere. Free-hand drawings 

 X about 900. (Description in text.) 



