466 C. C. MACKLIN. 



PLATE III. 



FIG. 24. Direct nuclear division in a connective-tissue cell, final stage. Cen- 

 trosphere between the nuclear parts. Across the slender filament joining these is a 

 strand of mitochondria. Nucleolus has not divided. Camera lucida drawing 

 from Preparation No. 2. from 5-day culture of y-day chick heart in Locke solution 

 (i per cent, dextrose); osmic acid vapor and iron hematoxylin. X 915. 



FIG. 25. Spireme in a bipartite nucleus. Prophase of mitosis. Nuclear 

 membrane and nucleoli are disappearing. Camera lucida drawing from Prep. No. 

 14, 9-1-15 (Lewis collection). Heart from 6-day chick grown in Locke (0.5 per 

 cent, dextrose) with a little yolk; fixed on third day of growth in Zenker; stained 

 with iron hematoxylin (this culture was originally stained with Mallory's connective 

 tissue stain). On account of the method of fixation the cytoplasmic details are not 

 shown. X 915. 



FIG. 26. Nuclei showing fragmentation. Camera lucida drawings from Prep. 

 No. 23, 12-1-15 (Lewis collection). 5-day chick stomach in Locke (0.5 per cent, 

 dextrose). Zenker; Mallory connective tissue stain. Culture grown for 6 days in 

 the same media. X 1,012. 



FIG. 27. Nuclei showing fragmentation. Camera lucida drawings from Prep. 

 No. 23, 24-11-14 (Lewis collection). 6-day chick stomach in Locke (i per cent, 

 dextrose) to which ethyl alcohol had been added to make approximately i per cent. 

 3-day culture. Osmic acid vapor and iron hematoxylin. X 1,500. 



