162 Jounsvon-Lavis—The Eruption of Vesuvius in April, 1906. 
not bombs, would be volcanie dumplings, as their mode of formation is identical 
with the method of preparing that dish. 
The contents of these dumplings are very similar to those found on the lava- 
streams of 1872, and described by Scacchi, and to those that can be collected 
from the surface of other a@ lavas. Vhey may be classified as follows :— 
A.—Scoria, etc., of the actual flow itself, that has become re-involved in the 
fluid rock. 
B.—Pieces of scoria, or lava, from earlier streams, over which the new one 
has flowed. 
C.-—-Fragments of rock, masonry, or any extraneous solids, picked up from 
the surface over which the lava flows. 
D.—Fragments caught in the passage of the lava through the lateral outlet. 
I}.—Extraneous pieces detached from the walls of the volcanic canal or 
chimney. 
F’.—Materials fallen in from the upper unoccupied part of the vent, and 
churned up in the lava beneath before it flowed out. 
G.—Masses ejected by the explosions, that fall upon a flowing lava. 
H.—Accretions in the magma itself ? 
It will be seen that there are many sources from which the nuclei of these 
dumplings may be derived; but in many cases it is not possible to say by which 
particular means they found their way into the flowing lava. As a general 
principle, the more complete the adhering crust, and the more fused and altered 
by heat the nucleus appears, the more likely is the origin to have been one in 
the interior of the volcano. With regard to section H, most of these supposed 
accretions are really only parts of the magma that has consolidated at great 
depths, and been again broken up and swept along by the more recent fluid 
magma. Others of this category are but very intensely metamorphosed materials, 
that are tending rapidly to acquire the same composition as the enveloping 
medium. 
The longer and more deeply seated the envelopment, the less are they likely 
to have a separate crust, or to float to the top as a component of the scum or 
dross of a lava-flow. The second stage of an enclosure in the magma is one of 
digestion of the former by the latter. They then more frequently appear as an 
enclosure of the lava-stream, with, as seen in section, an areola around them 
somewhat different in colour from the general matrix, and in which areola the 
