137 



Iniiml in or iiciir ^idiavfiiiiin >\v:iiii|)S. WluMi it w ;is I'diiinl l>y (•.irct'ii I cxiiiiiiii.'itioH 

 lliMt iKP |il;uils of tiu' gfiuis Hhii.< iitDw williiii (1111' mile i>i llu- iocalitv in wiiiili 

 the ti'st was niailt-, one of my ruriefiiiondeiits, witli a iiin^l admiralily (leveloiu'd 

 "sriiMititic imnuinatioii " stiggestetl that the pollen of the lilms may have been 

 cairicd liy the wiiiil ami (aiiglit by tiie si-eretioiis of tiie i;laniliii;ir iiairs, in such 

 <liiantiiy tiiat tiic iimoiiiil of toxieoih'iidi-ic aeid I'luitaiinil wmihl he siillicieiit to 

 jirodiice 1 lie initanl I'tlert. 



A niimlxT of root clumps of < '. iijx'claliilc. ('. piihe.-<r<'ii.'< and C parrilhrum 

 were obtained from I'iteher and Manda, and plaeed in the plant house under such 

 <'()nditions that leafy stems were formed and the experiments coiild he carried on 

 at intervals from I'eliniary 1 to .lune 1, IS'.M. In the plant house were no othei 

 known plants of |ioisonoiis intliienoe, and since dnriiij'- the greater part of this 

 pt'riod the country aronnd Minneapolis was covered with snow to tlie depth of 

 two or lliree feet, all danger from distant JUnni clump> and spliagnnm swamps was 

 held to be fairly (.xidmled. 



hetailed tests with the leaves of C. sjx'cldbi'r rulilied lightly on the skin of the 

 wrist, arm, fai-e or ear, were made with nine persons; of these, six were "p(ds- 

 oned" in a degree corresponding to tlie manner of application, in a time varving 

 from ten to twelve honrs. By a canvas of tlie students of the department it was 

 foun<l that nearly tiie same jiercentage wi'vv usually poisoned by Iilin-<. In order 

 pi confirm these results the test was repeated with the same result. .Still farther 

 repetitions were made by someof the persons concerned, until no (juestion as to the 

 ri'snlt remained. Tlu' unpleasant etiects of these tests were a severe drain on the 

 entiiiisiasm of the stdtjects, and the later tests on tliree persons made with C. pu- 

 l)i:sre)i!< were eipially marked. Nor is it a matter of surprise that similar effects 

 were shown by C. pdrrijloniui. It was next in order to ascertain whether this effect 

 was due to the mechanical injury resulting from piercing the skin by the pointe<l 

 hairs or to the corrosive action of the secretion found on the outside of the glob- 

 ular tips of the glandular Iiairs. To this end sei)arate tests were made by mate- 

 rial from C. ■•'peclubile. The hairs of each kind were taken from the leaf bv 

 means of a ])air of fine forcei)s and the tip pressed against the skin. Irritation 

 resulted from the contact of the glaii<liil,ir h.iir only, and in the form of a red 

 macule 1 to 2 millimeters in diameter. 



It was found, further, that the irritant action of tiic plant increased with the 

 development of the plant, and reached its maximiini with the I'ormation of the 

 seed-pod, from which it seems entirely reasonable to infer that this is a device, 

 and a very eflicient one, for the protection of the reproiluctivc Kodies durinsj the 

 period from pollination to the maturity of tiie seeds. 



