248 



KNOWLEDGE. 



JUI.V. 1911. 



show these marvellous little hairs, and they are 

 indeed " things " worth looking at \ery carefully. 



Figure 3 depicts 

 two hairs from 

 the leaf of the 

 Chili Nettle. 

 On this j)lant 

 t w o distinct 

 forms of hairs 

 are found: (1) 

 these branched 

 ones and (2) 



'^^^ 



l-IGURE 5. 

 hair Iroin the Itaf 



Figure 4. 



Hair from leaf of Mouse-ear 

 Haukweed. 



others of (juite different 

 form, that sting. No one 

 can deny that the branched 

 hairs are very formidable 

 looking structures, with their 

 barbs, or tinw sharp-pointed 

 branches springing out at 

 all angles from the surface 

 of the chief pedicel, which 

 is swollen at the base. A Slin, 



hair like this reminds one 

 rather of the teeth of the swonl-lish. l-'igure 4, 

 illustrating a hair from the leaf of the wild Mouse- 

 ear Hawkweed, shows another branched hair, some- 

 what similar to that of the Chili Nettle {Loasa). but 

 different in that its apex divides off into two wee 

 brandies, and its lateral ones are thicker and less 

 tooth-like. 



Perhaps Sfiiii^iii}> Hairs should be included amongst 

 the glandular, since the\- secrete a peculiar acrid 

 burning fluid, but they are so interesting that this 

 fact seems to warrant their being considered bv 

 themselves. 



Two species of stinging plants have been chosen 

 by way of illustration (1) the Chili Nettle ^see Figure 

 b). (2) tile Common Stinging Nettle (see Figure 5) 



Our own .Still 

 name from the 



"Urticii" lieing derived from ina 

 individual hair of this plant shiiws a 

 bulbous base composed of a large number of elastic 

 cells, a long pedicel, and an oval, slighth' enlarged, 

 sharp-pointed "cap" at tlir tip. TJie cells at the 

 hair-base contain the gland that secretes the acrid 

 Huid. By means of a duct that runs up the pedicel, 

 this fluid is conducted to the tip of the hair, and, if 

 till- point of the delicate cap be luoken or pressed 



against unwarily, the sharp point pierces the flesh 

 and the secreted fluid is injected. If, however, the 

 hair be damaged bclaic the cap. no uncomfortable 

 feeling is experienced because the stinging fluid docs 

 not then become injected into one's skin. 



Our own English species of Stinging Nettles 

 are unpleasant enough to handle roughh'. but 

 some e)f the foreign species, especialK' i'rficu 

 buccifeiii and C Halcrica are most formidalile 

 plants. In some of the East Indian species thev are 

 truly dangerous for, after the first pricking sensa- 

 tion has passed aw aw it is often followed bv that 

 of hot irons being rulibed 

 on the flesh, and the pain 

 increases to such an extent 

 that, after hours and some- 

 times days, the patient is 

 seized with s\'inptonis like 

 those following influenza and 

 lock- jaw, whilst sometimes 

 death results — especialK' when 

 the stinging has been caused 

 b\" one species of nettle from 

 Java. Our own species never 

 prove in an\' wa\' dangerous, 

 merely discomforting at the 

 time and sometimes for several 

 hours afterwards. Another 

 plant — Malpighia iireiis — has 

 dangerous stinging append- 

 ages, and thev are met with 

 ^i __ also in some species of Rhus. 

 An indi\'idual hair ol the 

 Chili Nettle (Loiisa) is 

 .f Willi Xrttl.-. luilbous at the base and 



there secretes 

 its acrid fluitl 

 w h i c h r u n s 

 up the pedicel 

 duct to tile hail- 

 tip. In this 

 case. howe\'er, 

 unlike our own 

 nettle, the tip 

 is not swiillen 

 into a distinct 



ing Nettle iUrtica) receives its 

 Inirnin.i,' iiroperty it possesses, 

 I burn. An 

 \'er\- enlar.t;ed 



,Slint;iug 



liair from tlie ieaf 

 Cliili Nettle. 



