258 Scientific Proceedings, Royal Dublin Society. 



The environment in tliis valley is less conducive to the maintenance of the 

 water balance of the plant than in the Lime Experiment Station at Eoseau, 

 Dominica ; the absence of a surface mulch is especially important. 



Xyleni Cylinder. 



The zonation is here very marked. The large vessels are rather densely grouped 

 circumferentially conferring the appearance of "spring wood," ivithin which 

 there occur bands of tangential parenchyma; these bands, it will be seen, tend 

 to be grouped radially. It will be evident that there was a rather definite 

 periodicity in tlie activity of the cambium. The presence of "sirring wood" 

 may indicate that leaf -production was vigorous over a rather limited period; 

 that, in horticultural parlance, there was a flush of growth. It will be remem- 

 bered that growth is generally most active during the dry season. The presence 

 of the radially grouped parenchyma bands may be due to intermittent periods 

 of desiccation about this time. 



O'Gaeea's Hillslope, Montserrat (fig. 4, Plate XIV). 



Lime trees free from die-hack. 



The steep talus slope ahove O'Garra's is dissected longitudinally by deep 

 ghauts, bordered by steep round-backed ridges. In the ghauts a certain amount 

 of shelter from winds is experienced, but the slopes of the divides are exposed 

 and dry. The lime plot examined occurs in one of these sheltered ghauts, at an 

 elevation of some 250 feet. The soil is a brown deep loam, and is characterized 

 by the presence over its surface of a very ^veil-marked layer of volcanic cinders 

 and small stones. They form a loose stone-mulch on the soil, and, when removed, 

 expose a plexus of lime rootlets, which ramify through a moist soil. 



Mean Annual Eainfall — 60 inches. 



Xylem Cylinder. 



A rather definite periodicity in the activity of the cambium is indicated. 

 The parenchyma bands, it will be observed, again are radially grouped, but they 

 tend to be distributed in the "autunm" rather than in the "spring" wood. This 

 is intelligible, if it be assumed that leaf -production was deferred vmtil the close 

 of the dry season, and that the tangential parenchyma resulted from intermittent 

 desiccation of the cambium during these months. 



Grove Botanic Station, Montserrat (fig. 5, Plate XIV). 



Lime trees free from die-back. 



The soil is very uniform in texture, deep, and uncompacted. A heavy mulch 

 of cane grass, cut from a neighbouring plot, covered the soil surface. In con- 

 sequence of this, and partly also because of the sheltered position, the soil at the 

 time of sampling (April, 1921) ivas moist to the touch. Well-grown specimens 

 of the leguminous shrub, Gliricidia maculata, occurred between the lime trees. 



Mean Annual Rainfall — 60 inches. 



Xylem Cylinder. 



The differentiation into zones simulating "spring" and "autunm" wood is 

 here scarcely perceptible. The zonation is mainly due to the parenchyma bands, 

 which are on the whole distributed at regular intervals radially; this is more 



