Joseph Marshall Flint 7 
clei of the syncytium are less numerous but still show the concentric 
arrangement about the growing buds, suggesting the continuance of the 
stress which, exerted in the younger stages, undoubtedly caused them 
to take this position. In the general syncytium the amount of exo- 
plasm has markedly increased. The fibrils are branched and distinct, 
but of unequal size, the latter characteristic being most obvious in those 
bounding the little lacunae in the interstices of the syncytium. ~~ 
In a pig 124 cm. in length the basement membranes are very sharply 
and deeply stained and show numerous fibrillar connections with the 
Fig. 5. 
Fie. 4. Alveolus from submaxillary gland of an embryo pig 121g em. long, 
showing the gathering of the exoplasm into fasciculi and increase in the size and 
number of the lacunar spaces. The dots represent partly fibrils cut in cross-section 
and partly granules of endoplasm situated on the fibrils. Fixed in Zenker’s fluid. 
Stained by Mallory’s method. Magnified 900 diameters. 
Fie. 5. Alveoli from submaxillary gland of pig’s embryo 16 cm. long, showing 
the fasciculi and the irregular direction of the exoplasm and nuclei caused by the 
different forces exerted by the growing alveoli. Stained by Mallory’s method, after 
Zenker’s fluid. Magnified 900 diameters. 
adjacent syncytium of the deposition zone. The anastomosing mass of 
fibrils now stands out with greater distinctness owing to the compact 
fascicular arrangement, a fact emphasized by interstitial lacune which 
increase proportionally as the exoplasmic fibrils are gathered into 
bundles or fasciculi that bound these spaces. To this fact may be due 
the apparent diminution in the relative number of fibrils. The changes 
that occur between the ages represented in pigs 124 and 16 cm. in 
length are of some importance. Besides a general clarification and in- 
crease in the distinctness and definition of the fibrils, they may now be 
