64 OTTO F. KAMPMEIER 
The most marked feature of the disposition of the lymphatics 
in the head is the relatively enormous expanse of a lymph sinus 
situated in the ventral and lateral cephalic territory. Its limits 
in a 26-mm. frog larva are shown in Hoyer’s sketches, illustrated 
in Wiederscheim’s ‘Vergleichende Anatomie der Wirbeltiere’ 
(7th et al. editions), and in the wax reconstruction of the vascular 
channels in the head of a toad embryo in figure 28. This lymph 
reservoir, which the writer designates the primary maxillary 
sinus (sinus lymphaticus primigenius maxillaris)? because eventu- 
ally it is resolved into the secondary lymph sinuses in the region 
of the jaws, is developed very early and, in general form, extent 
and proportions, is virtually complete in 9- or 10-mm. toad 
embryos, hence, at a period when most of the other lymphatics 
are still in the formative state. Figure 28 shows that this sinus 
does not possess a simple contour, but is composed of several 
interconnecting chambers of diverse shape and size. For con- 
venience and clearness, we may refer to the several subdivisions 
by different names. The broad, roughiy rectangular division 
(figs. 2, and 28, mand. si. max. prim.) on the ventral side of the 
head may be regarded as the mandibular one; it is the largest, 
the first to develop, and the other portions of the sinus arise 
from it by outgrowth and extension. In continuity with it 
anteriorly is the cireumoral division (figs. 1 and 28, circ. or si. max. 
prim.), which encireles the mouth opening. The third division, 
a pair of temporal chambers (figs. 3 and 28, temp. si. max. prim.), 
appears in the wax model as two lateral wing-like expansions of 
the mandibular sac; these extend as far as the pronephroi, where 
each contracts into a narrow duct which leads to the anterior 
lymph heart of the respective side. ‘The fourth division of the 
primary maxillary sinus may be termed the pericardial (figs. 3 and 
28, pericard. si. max. prim.); it constitutes a second path of 
communication between the mandibular and temporal sacs, but 
at a deeper level. It is paired and branches, as a more slender 
and somewhat plexiform channel, from the mandibular sac near 
4 Hoyer calls this the ‘Kehlsack’ and Jourdain ‘sac gulaire,’ and in my paper on 
the origin of the lymphatics in Bufo (’15) it is spoken of as the ventral cephalic 
sinus, but these terms are too general. 
