4 A. Barclay — On a TJredine affecting the [No. 1, 



89cidium is of a pale rose colour, but the free spores in mass are orange- 

 red, whilst the peridium is colourless. The secidia are first developed 

 on the lowest needles of an affected shoot, whilst in the upper ones they 

 appear in succession from below upwards. They are generally more 

 numerous on the lower than on the upper needles of a shoot. The still 

 unopened ^cidia protrude through clean rents in the epidermis, and, 

 when ripe, the peridium bursts with an irregular frayed margin (figs. 3 

 &4). 



General Appearance of TJredinal Affection. — The uredinal form is 

 much more frequently met with than the secidial just described. Its 

 general appearance is shown in fig. 19, which represents a fully deve- 

 loped specimen. This specimen had been preserved for a few days in 

 brine, and the needles were swollen somewhat unnaturally. The dimen- 

 sions of a fully affected needle are 1*60 x l'4i3 m.m., thus exceeding 

 those of the secidial affections. This form occurs sometimes on the 

 same host which bears the secidial form, but more frequently on 

 a separate tree. Presuming that the uredinal form is genetically 

 related to the secidial, this would not be surprising, since secidial fructi- 

 fication is usually less frequently developed than the uredinal. Whenever 

 the secidial form is met with, it is rarely unaccompanied by the uredinal 

 on the same host. In their general appearances alone, the two affections, 

 when fully developed, differ so much as to enable a distinction to be 

 made between them at a glance (compare figs. 18 & 19). The 

 densely aggregated needles of the uredinal form contrast strikingly with 

 the opener habit in the secidial form. But, in addition to this difference, 

 the uredinal form is distinguishable by its orange-red colour. It resembles 

 the secidial affection in always being confined to shoots of the present 

 season's growth, but the affected shoots are always small and never 

 attain the lengths so often seen in the secidial form. Indeed, the shoots 

 affected by the uredinal form of the parasite appear to be stunted in 

 growth, since no affected shoot ever measures more than 2 inches in length, 

 whilst in the measurements of unaffected shoots (given above in con- 

 trasting them with neighbouring shoots affected by the secidial form) 

 many exceeded this length. The aggregation of the needles also points 

 to a suppression in the long growth of the stem. It is probable, therefore, 

 that, whilst the secidial parasite stimulates growth in length of the stem, 

 the uredinal one represses it. A specimen gathered from the same host 

 which bore the secidial affection, and whose measurements were first given 

 above, measured only 2 inches in length though fully developed. The 

 separate needles here also curl up considerably, contrasting strikingly 

 with the neighbouring erect unaffected needles (fig. 19). Every needle 

 of the affected shoot is involved. 



