8 Reticulated Basement Membranes in the Submaxillary Gland 
observed running in very distinct fasciculi which bound still larger 
spaces. In some places there are groups of three or four nuclei sur- 
rounded by a common protoplasmic mass embedded in a dense fibrillar 
meshwork while at certain other nodal points of the fasciculi some 
nuclei have either little or no endoplasm at all. The basement mem- 
branes now have a much sharper outline and the fibrils of exoplasm 
that connect them with the general network do not appear so numerous 
because they are gathered into fasciculi. Many nuclei with a slight 
amount of endoplasm are observed flattened against the growing mem- 
branes with their long axis parallel to that structure. Now as the 
further development of the organ proceeds and as the alveoli grow 
closer together it must be obvious that the increments of exoplasm 
are in the form of fasciculi instead of individual fibrils. This, indeed, 
is in accordance with the appearances seen in digested specimens of the 
adult where a uniform network will be seen crossed by heavier strands 
of reticulum. In such cases, of course, this network represents the 
products of fibrillar deposits, while the strands, on the other hand, 
indicate fascicular deposition. As long as the alveoli are extending 
out into the general syncytium, sufficiently isolated to exert only the 
stress caused by their own growth, the nuclei and fibrils take the direc- 
tion mentioned above, but, in the latter stages, where, owing to their 
great numerical increase, the alveoli begin to encroach on each other, 
we have the stress exerted by one alveolus transferred through the 
syncytium to another so that excepting those immediately touching 
the basement membranes, the nuclei and cells occupy no definite posi- 
tion. Of course, even while this is so, the exoplasm embracing larger 
units of the growing organ may show by its direction the lines of stress 
and strain exerted by the more differentiated structural complexes. 
Pari passu with the changes that have been occurring in the develop- 
ing organs, a constant relative diminution in the quantity of syneytium 
and gland substance has taken place. Whether this is absolute or 
simply a relative difference it is difficult to say, but the gathering of 
the fibrils into fasciculi during the later periods of embryonic life has, 
undoubtedly, much to do with this appearance. However, to a certain 
point the syncytium, particularly the exoplasm, seems to increase and 
from that time on there is a constant apparent diminution until it is, 
finally, all changed into basement membranes or interalveolar frame- 
work. 
In a pig 19 em. in length the developing alveoli are now rather 
closely pressed together so that between them there is quite a good 
deal of embryonic connective tissue. The basement membranes are 
