PLANT DEIJMATTTTS 131 



everyone in tliis countiy, is the case of the Stinging Nettle. The 

 plant, particularly the leaves, is provided with stinging hairs, each 

 consisting of a long stiff shaft, narrowing towards the point, and 

 provided with a small bulbous tip. The portion of the shaft 

 immediately under tliis tip is not thickened and silicified like the rest, 

 so that a very slight touch is sufficient to break off the bulbous end. 

 The tip breaks off at a slant, leaving a fineh' pointed hollow shaft, 

 like the needle of a hypodermic syringe, which makes a puncture in 

 the skin through which the secretion can enter. The secretion, 

 which contains albuminoid substances, is injected through this into 

 the skin, and is a])parently accompanied by formic acid, which was 

 formerly thought to be the toxic principle ; this, however, is quite 

 inadequate to account for the severe symptoms that are sometimes 

 observed {e. g. the effect of the sting of tropical nettles, such as 

 JJrtica stimulans and Urtica urentissima, has been known to cause 

 severe continuous pain, tetanus-like symptoms, and even death). 

 A burning, j^ricking sensation follows the sting, and very soon each 

 spot touched is marked by a raised whitish wheal, surrounded by a 

 zone of reddened skin. In most cases in this country, this is the 

 worst that happens, but occasionally ])ersons with very delicate skins, 

 who are stung over considerable areas, or where the face and eyes are 

 aifected, may be rendered quite severely ill. In the Tropics, however, 

 much more striking effects are recorded. The most virulent of the sting- 

 ing nettles of India is Laportea crenulata. It has minute stinging 

 hairs which cause acute pain when touched, and the pain is increased 

 on bathing the affected part in w^ater. Girardinia Jietero'phylla 

 causes at most stinging pains, and the young tops are eaten as a 

 vegetable, as the Common Nettle is used in this country. On the 

 other hand, Girardinia zeylanica yields a fibre which has been used 

 for making clothes, with unpleasant results, owing to the extreme 

 difficulty experienced in entirely removing the stinging principles, 

 even in the severe processes to which the plant is subjected in order 

 to extract the fibre. 



Since the Stinging Nettle is never cultivated as a plant for 

 domestic decoration, injur3^ from it is alw^ays accidental, and the 

 results are so innnediately apparent as to leave no doubt of their 

 origin. The effects, too, are usually transitory, the wheals commonly 

 subsiding in a few minutes. Inmost cases no application is necessarv, 

 the cure being rapid and spontaneous. If the irritation is severe and 

 seems likely to be prolonged, the use of strong spirit is soothing, 

 partly because it coagulates any proteid present, and by its rapid 

 eva])oration has a cooling and analgesic effect. The " Grlyco-thymo- 

 line " of Messrs. Kress & Owen is also very useful, if applied full 

 strength on gauze or cotton -wool. 



II. The cases of Primula poisoning, however, are sometimes very 

 mystifying. Primula-dermatitis attracted a great deal of attention 

 about ten or fifteen years ago, although of course jjlenty of eailier 

 references to it are to be found. There is a certain monotony about 

 the clinical histories. In nearly every case the patient is afflicted 

 with an erythematous eruption accompanied by more or less swelling, 

 generally beginning on the hands, and spreading to the arms, face, 



