1902.] Seed-fungus o/Lolium temulentnm, L.. the Darnel. 27 



glow coincide with these two systems. For all those lines which 

 disappear in the negative glow, 7065, 4713, 4472, and the yellow line 

 5876 which nearly does so, belong to that system which, according to 

 Eunge and Paschen, is due to the gas helium ; whilst these which can 

 be seen at the negative glow with their full brilliance, 6677, 5016, and 

 4922, belong to the second system. 



This differentiation of the helium spectrum brought about by the 

 presence of mercury vapour might at first sight appear as a confirma- 

 tion of the idea of Runge and Paschen that helium is a mixed gas, 

 consisting of two different elements. But taken in conjunction with 

 the fact that the spectra of argon, neon, and krypton are all altered 

 by the same treatment, no reliance necessarily can be placed on the 

 argument. 



In conclusion it is worth while pointing out that a helium-mercury 

 tube containing the merest trace of hydrogen should be of value as a 

 standard tube for spectroscopic measurements. For it contains fourteen 

 standard lines, amongst them (C and F). Moreover all these lines are 

 of brilliance ten, very equally spaced from the extreme red to th# 

 violet, and with dark spaces between them. 



He 



Red 



7065 



Hg 



Green 



5461 



He 



Red 



6677 



He 



Green 



5016 



H 



Red 



6563 C 



He 



Green 



4922 



Hg 



Orange 



6151 



H 



Green 



4861 F 



He 



Yellow 



5876 



He 



Blue 



4713 



Hg 



Yellow 



5790 



He 



Violet 



4472 



Hg 



Yellow 



5769 



Hg 



Violet 



4359 



" The Seed-fungus of Zolium temulentum, L., the Darnel." By 

 E. M. Freeman, M.S., University of Minnesota. Communi- 

 cated by Professor Marshall Ward, F.R.S. Received June 6 

 —Read June 19, 1902. 



(Abstract.) 



Darnel (Lolium temulentum, L.) has been known since Roman times 

 for the poisonous properties of its grain. It was not, however, until 

 1898 that the presence of an often considerable layer of hyphse was 

 discovered just exterior to the aleurone layer of the grain ; to the 

 action of this fungus-layer the poisonous properties are presumably 

 due.* Nothing had hitherto been known regarding the method of 



* How far ergot and other fungi may be concerned is a disputed point. — 

 [June 24.] 



