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thrown off. On weak poorly-developed shoots, on the contrary, 

 the alga readily succeeds in getting a foothold and forcing its way 

 through the bark reaches the cortical tissues. In bad cases the 

 parasite may completely encircle the shoots and that for a length 

 of several inches. 



The practical conclusions to be drawn from the investigations are 

 as follows. Cutting out infected shoots in May, and spraying at 

 the same time of year proved useless, as also firing the bushes and 

 collar-pruning. The most hopeful line of treatment is to promote 

 healthy vigorous growth through good cultivation by attention to 

 soil and drainage, at the same time removing weak and twiggy 

 shoots. Overplucking should be strenuously guarded against, 

 nothing causing lack of luxuriance more frequently than this. 

 The destruction of infected leaves beyond those removed in 

 pruning is not advocated, the alga being found too abundantly 

 both on tea and other trees to be in this way materially reduced. 



In the disease dealt with above Gephaleuros is a parasite on the 

 tea plant ; algae that are endophytic on the higher plants are not 

 uncommon, but those that appear to be positively parasitic are 

 extremely rare. The following cases may be referred to. Three 

 other species of Gephaleuros are known to be injurious to foliage. 

 G. parasiticus on Galathea metallica, C. minimus on Zizyphus 

 jubata, and C. Coffeae on Cqffea liberica. Amongst the Proto- 

 coccoideae, ChJorochytrium and Phyllobiurn have been regarded as 

 parasites, but the researches of Klebs have shown that the injury 

 occasioned to the host-plant is practically nil. A closely related 

 genus, Rhodochytrivm presents, however, a decided advance in the 

 direction of parasitism. R. Spilanthidis, found in the leaves of 

 the Composite Spilanthes in Chili and Ecuador, is remarkable in 

 not possessing chlorophyll. The spores of the alga germinate on 

 the leaves of the host, the germ tube forces its way between the 

 epidermal calls, enters the internal tissues, and sends out branches 

 in the neighbourhood of the vascular bundles. Later a spherical 

 body is developed, through the enlargement of the original germ- 

 tube, in which the spores are formed. Another case is that of 

 Phytophysa Treubii which has been described as forming gall-like 

 swellings on the leaves and shoots of Pi lea in Java. Here again 

 the alga appears to be parasitic, and the tissue involved in the 

 formation of the gall is not only that of the cortex but also that of 

 the vascular system. Finally there may be mentioned the 

 remarkable Phyllosiphon Arisari. This alga, parasitic in the 

 leaves of Arisarum vulgare, is a member of the Sipl 

 producing a richly branched system of tubes, without the 

 formation of cross- walls. Sections through the infected areas of 

 the leaf show dichotomously branched filaments which grow 

 vigorously in the intercellular spaces, and form fruiting-bodies. 

 The alga is regarded as a parasite, in that the filaments, although 

 not piercing the cell-walls of the host, cause the death of those 

 cells with which they come in contact, and in this way produce 

 the large yellow blotches characteristic of the disease. 



A. D. C. 



oneae 



