25] 



CHAPTER I. THE CELL. 



83 



FIG. 58. Raphides (fc) in a cell of a bulb-scale of Urginea 

 arirott(x 200). 



choke, Dahlia, Globe Artichoke) the cell-sap is rich in inulin, a 

 substance having the same percentage composition as starch (re- 

 presented by the 

 formula C G H 10 5 ): 

 when a portion of 

 tissue of one of 

 these plants, such 

 as a piece of the 

 tuberous root of 

 the Dahlia, is kept 

 in spirit, the inulin 

 slowly precipitates 

 in the form of 

 sphserocrystals 

 (Fig. 59) adhering to the walls. 



The cell-sap also very frequently holds colouring-matters in 

 solution ; for instance, the colouring-matters of most red and blue 

 flowers (erythrophyl and anthocyanin) ; of many fruits, such as 

 the Cherry and Elderberry ; of 

 " copper leaves," such as those 

 of Copper Beech and Hazel, and 

 of the Beet-root. 



25. Cell - Formation. 

 The formation of a cell is ne- 

 cessarily dependent upon a 

 pre-existing cell ; the direct 

 development of a cell from the 

 necessary chemical substances 

 that is, spontaneous genera- 

 tion has not yet been ob- 

 served. Moreover, it can only 

 take place when the proto- 

 plasm concerned is in the 

 embryonic condition ; as, for 

 instance, in growing- points, 

 germinating spores, etc. 



The development of cells 

 always takes place in such 



Wise that the whole Or part Fm. 69.-Sphajrocrystals of inulin in the 



Of the protoplasm of a Cell, tissue of the tuberous root of Dahlia variaUlis 

 ,, 7, T after prolonged action of alcohol. (After 



the mother-cell, undergoes re- strasburger: x 240.) 



