1910. ] Hydrochloric Acid in the Gastive Tubules. 8] 
At the points mentioned of the tubules in which the blue deposit was 
observed, the central lumina was found to be thickly lined with aggregations 
of blue granules of irregular size and shape, causing the lumina to present a 
“wavy or jagged appearance. (See Plate 7, figs. 3, 4.) 
Besides the occurrence of the deposit already observed with the low power, 
lines of blue in certain instances could be observed passing between the 
central lumina and the parietal cells, and ramifying within these. As a rule 
only one, but occasionally two, of these side branches penetrated a cell. (See 
Plate 7, fig. 5.) Sometimes as many as three or four branches connected 
at short intervalsfrom each other with the central lumen containing Prussian 
blue, were seen to pass towards an individual cell. In some cases a branch 
passed partly round a cell before entering it ; in others,a branch curved round 
a cell and disappeared as if to reach a parietal cell situated at a greater 
distance from the lumen or in another plane, while another branch in close 
proximity entered the cell in the immediate neighbourhood. Occasionally 
branches extending to opposite sides were connected with the central lumen 
at the same point. On entering the cell the branch usually divided and sub- 
divided, the fine canaliculi penetrating the depth of the cell. Local aggrega- 
tions of the Prussian blue in the delicate canaliculi gave them, in many 
instances, a beaded appearance. ‘Their course was frequently very wavy or 
serpentine. 
Branchlets were frequently directed towards the nucleus; in many cases 
they curved round it to reach the cytoplasm on the far side; in others, they 
appeared to terminate in its immediate vicinity. Aggregations of the precipi- 
tated Prussian blue were frequently found close to the external border of 
the nucleus, but with the exception of one or two instances in which a 
definite decision could not be made, the canaliculi did not appear to enter the 
structure. (See Plate 7, fig. 5; Plates 7 and 8, figs. 6, 7, 8, 9, 10, 11.) 
Sometimes the canaliculi formed a fine intracellular network (see Plate 8, 
fig. 11); in some instances an aggregation of the deposit appeared to indicate 
the terminal point of a free branch. Deeply pigmented oval or round areas, 
varying in size, and sometimes connected with canaliculi, were occasionally 
Inet with in the course of the central lumen or in the cells, which suggested 
reservoirs containing an accumulation of the secretion in which the reaction 
had occurred. (See Plate 8, figs. 11-12.) 
In certain of the parietal cells adjacent to lumina containing a large 
amount of the deposit, the intracellular ramifications as such were not clearly 
visible, but were indicated by minute isolated aggregations of Prussian blue 
occurring here and there in the cytoplasm. (See Plate 8, figs. 11—12.) Apart 
from the ramifications of the blue canaliculi and the above-mentioned 
VOL, LXXXIIT.—B, G 
