296 
lationships of this vessel before the separation of the systemic and 
pulmonic trunks. Fig. 9 is an outline of the aortic arches, in the 
fine reconstruction by TANDLER, of an embryo after the separation of 
the arterial trunks. 
Harriet LEHMANN has published a figure of the aortic arches of 
a pig embryo about twenty-one days old in which there is a vessel 
connecting the systemic and pulmonic arches. As shown in Fig. 10, 
it arises from the central portion of the fourth arch, and passing 
Fig. 10. Reconstruction of the aortic arches in a pig embryo of the 21st day 
(after LEHMANN) X about 18 diameters. 
dorsad and cephalad unites with the pulmonic arch near the union of 
the latter with the aortic root. It is also connected with the aortic 
root by an independent branch. It is rather difficult to decide whether 
the main path of the vessel in this specimen is from the fourth arch 
to the aorta or from the fourth to the pulmonic arch, but from the 
other figures in Miss Lenmann’s paper and also on account of the 
findings of TANDLER in rat embryos, I think that the latter is more 
probable. 
F. T. Lewis, as reported before the American Anatomists, finds 
only irregular vessels between the systemic and pulmonic arches jin 
the pig. In his specimens, so far as reported, he did not find a com- 
plete vessel, and holds to the view that the great irregularity of; the 
vascular elements will not admit of the conclusion that there is a fifth 
aortic arch in the pig. 
