312 



Mycologia 



indicate their disorganization. No further cytological evidence 

 could be observed between the parasite and rust. The prepara- 

 tions were examined carefully for haustoria or other penetration 

 of the rust mycelium by the parasite. Where mature aecia are 

 infected the parasite appears to be concerned in suppressing spore 

 distribution. The pycnidia develop in the aecial cup with the 

 peridia still entact. Only a few mature spores are found below 

 the pycnidium. The mycelium of the parasite ramifies through- 

 out the spore mass and appears to engulf the spores. Several 

 instances were found where the pycnia were parasitized upon the 

 upper surface of leaves. Considerable disorganization of the 

 pycnia were observed to follow such infection. I have been 

 unable to find in the literature where this rust stage has been re- 

 ported infected by Darluca. 



My observations indicate that the resultant effect of the para- 

 site is to prevent aecia maturing and suppress spore distribution. 

 Owing to the deep origin of the aecia, the pycnidia of the parasite 

 are submerged or endogenous and not easily recognized in con- 

 trast to its growth on other species of rusts. This sort of hidden 

 relation between parasite and rust may be more common than 

 heretofore supposed. 



Sappin Trouffy 16 has studied Darluca filum on the uredinia of 

 Puccinia Porri. He finds the mycelium ramifies throughout the 

 sori and becomes attached to the urediniospores by " crampons." 

 It is stated that the parasite assumes a " role destructeur." His 

 illustration (Fig. 2) shows the mycelium of the parasite in the 

 uredinia with apparent haustoria penetrating the sub-basal cells 

 of the sori as well as the " crampons " attached to spores. He 

 finds the parasite presents the same characters on Puccinia grami- 

 nis and Puccinia Menthae. I have been unable to observe this 

 situation in any of my preparations. 



The original description of Darluca by Castagne 4 and that given 

 by Saccardo 15 is different with respect to the morphology of the 

 spores. I have not been able to determine the reason for the 

 change from the original description by Saccardo. 15 The follow- 

 ing discussion presents the facts so far as I am able to determine 

 regarding the presence or absence of bristle spores. 



