2 A. Barclay — O71 a TJredine affecting the [No. 1, 



disappears entirely during the rains in July. Whether the two forms in 

 which it was met with, and which I shall for convenience describe as the 

 secidial and uredinal, do really stand to one another in this relationship it is 

 impossible to determine without experimental evidence, and I have had no 

 opportunities for performing the necessary experiments. From other cir- 

 cumstances, however, the existence of such relationship appears to be 

 probable. I could find no trace of any teleutosporic form for this para- 

 site either on the same or on any other host. Although I examined 

 many uredo pustules with care, I could never detect any separate form of 

 persistent spore among them. This, however, may have been due to the 

 fact that all the specimens at my disposal for investigation were gathered 

 during May, and, if teleutospores are formed at all in the uredo beds, it 

 is quite possible and probable that they are developed later. The 

 question as to whether the mycelium in either form is perennial requires 

 further investigation. I am mainly influenced in regarding the mycelium 

 in both instances as not perennial by the fact that the affection in both 

 cases is confined entirely to shoots of the present season's growth, as will 

 be more fully explained below, and that the whole of the affected shoot 

 withers and dries up completely when the fungus has completed its 

 existence (fig. 20). 



In describing these two forms of the affection, it will be convenient 

 in the first place to give a short account of the general naked eye 

 appearances of each, and then to proceed with the description of their 

 minute characters. 



General Apjpearance of the JEcidial Affection. — When fully developed 

 the affection is very conspicuous : large masses of tissue are affected, and 

 the pale yellow colour of these parts contrasts strikingly with the 

 surrounding green foliage. The fungus always attacks a young terminal 

 shoot, and the distortion caused, partly a real and partly a pseudo-hyper- 

 trophy, renders it still more conspicuous. Moreover; the affected part 

 assumes a drooping habit due apparently to the weakening of the tex- 

 ture of the stem by the mycelium which largely pervades its whole 

 tissue. 



The general appearance of a young affected shoot is well shown in 

 fig. 17. In this stage, the affected needles lie against one another, 

 embracing the stem instead of standing out from it, as the natural 

 needles are seen to do in the same figure. The stem and needles 

 are already in this young stage considerably thickened. The whole 

 of the affected part has a uniformly pale yellow colour. Conspicu- 

 ous as it already is, it becomes much more so when further advanced. 

 The thickening of the needles and stem increases greatly. The dimen- 

 sions of the transverse section of a normal needle on an average are 



