Fungus of Lolium. 283 



The ovary used in this plate was o])taiiie(l from a plant prowinj^ 

 in the Melbourne University grounds. It was apparently the pro- 

 <luct of a second fl(tAverin<^ resulting' from heavy early autumn 

 rains. Since all attempts t.) obtain this form again have l^en 

 unsuccessful, it might be argued that it cannot be the fungus found 

 associated with Lolium pererme. Ihis may be so, but it is just 

 probable that since the ovary represented a sec-ond flowerin<: the 

 fungus may be growing more actively than the developing grain, 

 the grass being naturally weakened by its previous flowering, so 

 that the fungus may have been in a suitable condition to grow 

 ■on the artificial medium provided. 



Concerning the Function of the Fungus. 



It has been suggested that the fungus associated with Darnel 

 grass possesses the power of nitrogen-fixation. Hiltner (5) was the 

 first to formulate this idea, and after testing it by experiment, he 

 concluded that Lolium temulentum grew as well in nitrogen-free 

 sand, as in sand to w^hicli nitrogen, in the form of potassium 

 nitrate, ' had been added as a fertiliser. As a control he grew 

 Lolium italicum under similar conditions. This species, at the 

 time of Hiltner's work (1899), w^as regarded as being fungus 

 free. Later, Freeman (1903) found in a sample of 59 grains two 

 contained the fungus and 57 were devoid of it. This, although it 

 is a low percentage of infected grains, could introduce a serious 

 error into such work when using this species as a control. 



The experimental methods employed by Hiltner are also open to 

 criticism. He planted grains of both species in pots, which were 

 <x)mpletely nitrogen-free, but he watered one set of two with tap- 

 water, w^hicli contained 0.84 mg. of nitrogen per litre. To the 

 •other set of two lie gave in addition 50 mg. of nitrogen in the 

 form of potassium nitrate. These pots were apparently left exposed 

 io the air, and so were subject to many sources of external nitrogen 

 <X)ntamination, the most formidable perhaps being nitrogen-fixing 

 bacteria. 



An experiment carried out in this manner could not aim at deter- 

 mining whether the fungus is capable of fixing free atmospheric 

 nitrogen in the compelete absence of coinhinal nitrogen. How- 

 ever, as several investigators have shown, Herthelot (17), Purie- 

 witsc-h (18), and Latham (19), that certain fungi can fix free 

 nitrogen if supplied with a small amount of this element in a coin- 

 l)ined form, the results given by Hiltnej- might liave some U'aring 

 on the latter point. 



