8 4 



BOTANY FOR BEGINNERS 



CHAP. 



the leucoplasts being concerted into chloroplasts. The leuco- 

 plasts perform the important work of converting sugar into 

 starch. The starch grains are produced on the outside of the 

 leucoplasts, not inside as in the chloroplasts. They are of 



a denser consistency than 

 chloroplasts, and somewhat 

 flattened in shape. Qhr$mo- 

 plasts are masses of proto- 

 ptesm which are saturated 

 with colouring matters other 

 than chlorophyll. 



FIG. 107. Leucoplasts. A, C, D, E, 

 viewed from side ; B, from above ; 

 E, one changing colour. (X54O.) (S.J 



FIG. 108. Cells from pulp of Tomato, 

 showing chromoplasts. 



EXPT. 79. Cut a thin section from a Beetroot, and mount it in 

 water. Examine under a low power. Note 



(i) The large cells with their thin cell-walls. 



(ii) The protoplasm which lines the cell-wall. 



(iii) The coloured cell-sap which does not escape from uninjured 

 cells. 



(iv) Dip a fresh section in alcohol for half a minute, before examin- 

 inc* it. The coloured sap oozes out because the protoplasm has been 

 killed. 



EXPT. 80. Obtain a few Fern Prothalli from a gardener. Mount 

 a small one in water, and examine with a low power. Note 



(i) The cells crowded with chlorophyll corpuscles. 



(ii) Many of the chlorophyll corpuscles are undergoing division, as 

 is shown by their shape. Grains shaped like an hour glass are under- 

 going division. 



(iii) Place a prothallus in a watch glass and cover with alcohol, and 

 leave it for half an hour. Mount and examine. Note The colouring 

 matter has been dissolved out of the corpuscles, but they still retain 

 their outline. 



