THE LEMON 71 



C. Make a cross section of a fruit and notice whetlier the wall of the 

 ovary can be seen distinct from the seed coats. Compare the dock 

 fruit in this respect with the fruit of the buttercup shown in Prin- 

 ciples, Fig. 161. Such a fruit as either of these Is called an akene. 



50. A nut, the acorn. 



A. Sketch the entire acorn, side view, with the base inclosed in its invo- 

 lucre, the "acorn cup." Note the remains of the stigma at the top of 

 the acorn. 



B. Cut a cross section of the acorn about midway of its length. Note 

 the hard pericarp and the seed, with thick cotyledons. 



C. Make a drawing of a lengthwise section of the seed out at right angles 

 to the surfaces where the cotyledons join. Look for the plumule 

 and the hypocotyl. Note and describe the testa. Test the cotyledons 

 for starch and for oil. Note the taste of the seeds. How are they 

 disseminated ? 



If possible, compare the acorn with such other nuts as the chest- 

 nut and the hazelnut. 



5 1 . A berry, the tomato. 



A. Study the external form of the tomato, and note the persistent calyx 

 and peduncle. 



B. Cut a cross section at about the middle of the tomato. Note the 

 thickness of the epidermis (peel off a strip) aijd of the wall of the ovary. 

 Note the number, size, form, and contents of the cells of the ovary. 

 Observe the thickness and texture of the partitions between the cells. 

 Sketch. What changes in the fruit of the pepper (Principles, Fig. 166) 

 would make it resemble a tomato ? Note the attachments of the seeds 

 to the placentas, and the gelatinous, slippery coating of each seed. 



The tomato is a typical berry, but its structure presents fewer 

 points of interest than are found in some other fruits of the same 

 general character, so the student will do well to spend a little more 

 time on the examination of such fruits as the orange or the lemon. 



52. A leathery-skinned berry, or hesperidium, the lemon. * * Pro- 

 cure a large lemon which is not withered ; if possible, one which 

 still shows the remains of the calyx at the base of the fruit. 



A. Note the color, general shape, surface, remains of the calyx, 

 knob at portion formerly occupied by the stigma. Sketch 

 the fruit about natural size. 



B. Examine the pitted surface of the rind with the lens, and 

 sketch it. 



