THE CALYX AND COROLLA 199 



The colouring of fruits is due to a similar cause. From a ripe 

 Tomato remove a small quantity of the inner pulp, and mount 

 it directly on a slide under a cover-slip, or if the pulp be not very 

 deliquescent add a little water. 



Note under a low power the pulp, composed of numerous 

 spherical or oval cells, which are more or less completely 

 separate. 



Examine a single cell under a high power, and observe the 

 numerous granules (the chromoplasts) of an orange or red 

 colour, and irregular form : they are often, like the leukoplasts, 

 grouped closely round the nucleus. 



Observations of similar bodies should be made in other brightly 

 coloured fruits, the Eose Hip will be found to be a very good 

 example, and in it the relation of the chromoplasts to the chloro- 

 phyll-granules may be observed, by comparing hips in which the 

 colour is turning. They should also be examined in petals of 

 various plants, e.g. of Ranunculus, Tropceolum, and coloured hairs, 

 e.g. those on the stamens of Cucurbita, &c., &c. 



Sections should also be made through the nectaries, 

 which occur in many flowers, e.g. in Fritillaria, Ranun- 

 culus, &c., in connection with the petals or on the recep- 

 tacle : these will be found to be essentially similar in 

 structure to, and may be treated in the same way as, the 

 glands described above on p. 142. 



