386 The Nerves and Muscles of the Leg 
Fie. 2. Adductor group in embryo XXII, length 20 mm., age about seven 
weeks. The adductor brevis and the gracilis muscles are shown cut out a 
short distance from their attachments. In ‘“‘a” the relation of the nerve to 
the belly of the gracilis muscle is shown; in “b” that to the belly of the 
adductor brevis. The muscles are represented as semitransparent so that the 
intramuscular course of the main nerve trunks may be followed. 
Fic. 3. The hamstring group in embryo XXII. The belly of the semi- 
tendinosus has been cut out so as to show the deeper structures. 
Fic. 4. The gluteal and obturator internus muscle groups in embryo 
CXLIV. The gluteus maximus muscle, except at its attachment to the femur, 
is represented merely by an outline. The central portion of the belly of the 
gluteus medius has been cut out to reveal the gluteus minimus. The tibial 
nerve is cut off near the plexus, the peroneal nerve more distally. 
Fig. 5: The gluteal and obturator internus muscle groups in embryo XXII. 
The m. gluteus maximus and the lig. sacrotuberosum are shown in outline. 
The central part of the belly of the gluteus medius is cut out. The tibial 
nerve is cut off near the plexus. 
PLATE IX. 
Six figures to illustrate the early differentiation of the musculature of the 
crus and pes. 25 diam. 
Fic. 1. Peroneal and extensor muscles and nerves of the crus and pes of 
embryo CXLIV, length 14 mm., age about five and a half weeks. The pero- 
neal muscles and the m. extensor digitorum longus are made semitransparent 
in order to reveal the deeper muscles and nerves. 
Fic. 2. Peroneal and extensor muscles and nerves of the crus and pes of 
embryo XXII, length 20 mm., age about seven weeks. The peroneal muscles 
and the m. extensor digitorum longus are represented semitransparent. 
Fic. 3. Superficial plantar musculature and nerves of the crus and pes of 
embryo CXLIV. 
Fic. 4. Deep plantar musculature and nerves of embryo CXLIV. The 
gastrocnemius and flexor digitorum longus and the main trunk of the medial 
plantar and a part of that of the lateral plantar nerves have been removed. 
Fie. 5. The superficial plantar muscles and nerves of the crus and pes of 
embryo XXII. 
Fic. 6. The deep plantar muscles and nerves of the crus and pes of em- 
bryo XXII. The gastrocnemius and flexor digitorum longus muscles and the 
greater part of the tibial nerve have been removed. 
PEATE) XX. 
Two figures to illustrate the early stages in the development of the pudic 
nerves and the distal portion of the sympathetic system. 
Fic. 1. Medial view of the right half of the distal portion of embryo 
CXLIV, length 14 mm., age about five and a half weeks. Enough of the sur- 
rounding undifferentiated mesenchyme has been removed to reveal the course 
of the nerves and the neighboring blood-vessels. The intestines are not 
represented. 25 diam. 
Fic. 2. Similar view of the right half of the distal portion of embryo 
XXII, length 20 mm., age about seven weeks. 20 diam. 
