loool B \RBER-FRU ITS AND SEEDS OF CUCURBIT ACEAE 297 



other species described. The surface is roughened and covered with 

 spines and hairs, of which, as described below, there are four forms. 



1. Epicarp.— This layer is composed of small flattened cells 13ft 

 high, with slightly thickened walls. In surface view they are polyg- 

 onal and 20 fi in diameter (fig. 29). 



Very striking are the prickles (emergences), each being a long 



mm 



I fig 



They have a constricted base, the epidermis of which consists of thin- 

 walled cells. Above this base the epidermal cells elongate and become 

 thickened. Over all the surface of the prickles are borne slightly 

 curved, single-celled, conical hairs (often 135 /* in length), with 

 extremely thick walls (fig. 27). They are very stiff and turn sharply 

 backward. Doubtless they play an important part in the dispersal 

 of the seeds, acting as barbs to fasten securely the prickles, and thereby 

 the fruit, to passing animals. Similar pointed but not deflexed hairs 

 occur on the epicarp, either singly or in pairs. 

 At the end of the prickle there is a thin-walled capitate hair, con- 

 ing of a stalk of several short cells and a single-celled glandular 

 head (fig. 2 j). 

 Among the prickles there are also large glandular hair^. reaching 



(figs 



The foot con- 



"■- 



of one or two enlarged epidermal cells and is surrounded by 



1 1- . . . . . n .o^^rritfwi and 



From 



c dls but slightly smaller. *-.««-««. 



thin-walled, the hair tapering gradually and ending with short gland u- 

 lar cells. The prickles become entangled in the hairs and do not fall 

 even though detached from the pericarp. 



Off. 



(fig 



^cellular or several-jointed, reaching a maximum length of 54° "• 

 The end cell is conical and not glandular as in the preceding hair. 



cell. 



umerous stomata occur among these hairs. 

 H y pod erm. —One or more lavers of very 



an inconspicuous layer just within the epicarp. Ahv 



. rmal cells of the constricted base of the prickle are al^o verj 



"^te and thin-walled. These together with the thin-walled epi- 



pod 



Crm,> Permit the prickle 



Pnckle l he cells are elong; 

 Plts (fe. 26). 



Inth< 



