BY C. C. BRITTLEBANK. 655 



(Pl.xix., figs. 2-6). The growth of the parasite being more rapid 

 than that of the host, the bark of the latter is weakened or 

 forced off, the space being occupied by Loranth cells. By this 

 continued outward pressure and invasion, the base of the parasite 

 completely surrounds the branch, which is forced off and falls 

 away beyond the junction, and is then overgrown by the base of 

 the parasite. The medullary rays are seldom, if ever, invaded in 

 this type of graft (Pl.xix., figs. 5-6). 



In microscopic sections taken from the base of the Loranth, 

 the cells are found to be crammed with starch granules, as indeed 

 is the whole of the parasite, even from the early stages of its 

 growth. If the excrescence be sawn through, smoothed, and 

 then placed in a bath of dilute iodine, the portion formed by the 

 Loranth-tissue will become black, owing to the great quantity of 

 contained starch. A clear, well-defined junction can then be 

 observed (Pl.xviii.,figs.5-6). 



Branches bearing parasitic growths when compared with others 

 from the same tree, are lacking in starch to a marked degree. 

 Observations are, however, being carried out to ascertain if the 

 sap returned to the host from the Loranths is capable of . 

 supporting and building up the host. Trees, especially Casuarina 

 and Acacia melanoxylon, perish when plants of Loranthus 

 Exocarpi have been established on them for some years. The 

 cause of death is not yet definitely known, but in this case it is 

 probably owing to the great quantity of starch stored within the 

 tissues of the Loranths, thus bringing about a slow starvation of 

 the host. 



During the year 1907, and on subsequent dates, small branches 

 bearing Loranths, as well as others which were free, were ring- 

 barked, the cambium being completely scraped away, as well as 

 some of the sapwood. These branches were examined a month 

 later, and in all cases the Loranths were still fresh, while the 

 other branches were dead, or nearly so. On 4th April of the 

 present year, similar experiments were carried out, and the 

 Loranths were quite fresh on June 2nd following. 



A seed with two embryos is represented in Plate xv., fig. 30. 



