208 ART. 3.— B. KOTÔ: 



tion and local collection of crystals from melts under low pressure 

 at or near the surface within the vent, where the temperature is 

 lower than the interior, that is to say, a subaërial product, during 

 the Strombolian activity (Pereet) ; for this reason we have lava- 

 scum and cordierite -bearing pumice. Chemically speaking, they 

 seem to correspond to the ground ma s s (p. 196)^^ of andésite, 

 the phenocrysts of early crystallization sink down to a lower liorizon, 

 thereby producing the total effect of selective crystallization- differ- 

 entiation. The crystalline éjecta, e.g., ordinary ceramicites, on the 

 other hand, are the assemblage or secretion of chemically light 

 crystals in a rather lower horizon, buoyed up through the magma 

 to the surface, assisted by the ascent of gas and the circulation 

 of liquid lava within the vent.'^ It is difficult to say anything 

 about the origin of the magma, whether primary or syntectic, 

 although the former is for the greater part higlily probable. 



The ceramicites are consolidated leucocrates of andesitic magma, 

 formed close to the wall of the vent at a shallow horizon. The 

 volcanic scums (p. 187), the gabbroid éjecta (p. 190) and the 

 ceramicites all seem genetically of the same origin, differing only 

 specifically. They probably correspond to Lacroix' s enclaves 

 homœgènes or Haeker's cognate xenoliths. 



4) Solid Ejected Blocks of Juvenile Lava.— The ' live ' lava makes 



1) "Within the exogenous contact zone of the oligoclase-granite in the Orijiirvi region, 

 Pentti Eskola mentions a greater number of cordierite-gneisses, skarns and ores, which are said 

 to be formed by pnenmatolytic metamorphism under photonic condition. It will, however, 

 apj)ear at first sight paradoxical to tind their analogous prodiicts among the juvenile recent 

 éjecta of Sakura-jima. 



It is w^orthy of note here, that he often speaks of the conversion of plagloclases into 

 cordierite, which is expressed in the term of chemical formiilas. The present writer is also 

 convinced of the fact, that there exists an intimate relation between feldspars and cordierite, the 

 latter often poikilitically enclosing the former with the corona of glass between them. See 

 PI. XXn. Fig. 2. ' On the Petrology of the Orijiirvi Region in Southwestern Finland.' Bull. 

 Com. Géol. de Finlande, No. 40, 1914, pp. 167-262. 



2) Perret, ' The Circulation System in Halemaumau in Lava Lake during the Summer of 

 1911.' Amer. Jour. Sei., 1913, p. 345. 



