54 



ORGANOGRAPHY. 



component cells of compound hairs may be also variously ar- 

 ranged, and thus give a variety of forms to such hairs. Com- 

 monly their cells are placed end to end in a single row, so that 

 the hairs assume a more or less cylindrical form ; but when the 

 component cells are contracted at the points where they come in 

 contact, they become moniliform or necklace shaped {figs. 119 

 and 120). When the cells below are larger than those above, so 

 that the hairs gradually taper upwards to a point, they become co- 

 nical ; or when gradually larger from the base to the apex, the hairs 

 are clavate or club-shaped {fig. 121); or when suddenly enlarged, 



Fig. 119 



Fig. 122. Fig. 123. 



Fig. 120. 



Fig. 124. Fig. 125. 



/Fig. i: 

 nica 

 Hoo 

 late 



Fig. 126. 



Fig. 119. Moniliform hair of Virginian spiderwort (Tradescantia virgi- 



nica) Fig. 120. Moniliform hair of Marvel of Peru (Mirabilis Jalapa). 



Fig. 121. Clavate hairs. Fig. 122. Capitate hairs. Fig. 123. 



Hooked hairs. Fig. 124. Glochidiate or barbed hairs. Fig. 125. Stel- 

 late hair from the Ivy. Fig. 126. Peltate hair from Malphighia wrens. 



at their apex into a rounded head, ca'pitate {fig. 122). "When the 

 terminal cells of hairs are terminated by a hook on one side 

 pointing downwards, such hairs are termed uncinate or hooked 

 {fig. 123) ; or if ending in two or more hooks at the apex, they 

 are glochidiate or barbed {fig. 124). Such hairs again, instead 

 of being erect, or more or less oblique upon the epidermis, may 

 develop horizontally in a more or less circular manner, and 

 form stellate hairs, as in the Ivy {fig. 125) ; pr two of the com- 

 ponent cells may develop in opposite directions from another 

 cell raised above the level of the epidermis, so as to produce 



