OYTOLOGICAL CBANGES PRODUCED IN DEOSEEA. 215 



in one to two days. Fig. 19 shows such a cell nearly quite re- 

 cuperated after twenty-four hours. 



Nucleic Acid (stains Blue) (figs. 20 — 23). — The acid was 

 prepared absolutely pure by Dr. Griibler. The powder was 

 made into a paste, and a piece about the size of a pin's head 

 placed on the centre of a leaf which folded up and secreted 

 violently for one to two days. At another time dry powder, 

 or minute particles of the paste, were dusted on the tentacles, 

 which then bent inwards and secreted copiously for one to two 

 days. 



In both cases the leaves commenced to reopen in one to 

 three days, and were perfectly uninjured. 



Five Minutes after Feeding (fig. 20). — The cell walls 

 stain a much deeper blue than in controls. The cytoplasm 

 shows very great vacuolation, and has contracted into thick 

 strands, forming a network which stains very deep blue, and 

 has a coarsely granular or knotted appearance. The nucleus 

 has shrunk considerably. The nuclear membrane and nuclear 

 chromosomes are unchanged. The nuclear plasm stains bluer 

 than normal, is somewhat aggregated and less dense. The 

 nucleolus is normal in size, but stains purple. 



One Hour after Feeding (fig. 21). — The cell walls and 

 cytoplasm show no further change. The nucleus has become 

 irregular in shape, and usually has elongated transversely to 

 the long axis of the cell. The nuclear periphery is distinct, the 

 membrane staining dark blue and remaining distended. The 

 nuclear plasm has contracted away from the nuclear membrane, 

 and forms a small, compact, purple sphere round the nucleolus, 

 suspended in the nuclear cavity by fine radiating threads 

 attached to the nuclear membrane. A homogeneous fluid 

 which takes a pale blue stain appears to fill the space be- 

 tween nuclear plasm and membrane. The chromosomes are not 

 distinguishable. The nucleolus stains dark crimson. From- 

 mann's clear zone is obliterated by the closely contracted 

 nuclear plasm. 



One Day after Feeding (fig. 22, a, b). — The cell walls 

 stain paler blue. The cytoplasm is very pale blue, and is 



