266 C. W. PRENTISS 



purpose in the present paper is to describe the rudimentary gang- 

 lia which occur between the first cervical nerve and the vagus, 

 ganglia which I shall refer to as the hypoglossal ganglia because 

 of their undoubted connection with this nerve. My descriptions 

 will necessarily deal with the development of the last four cranial 

 nerves, the glosso-pharyngeal, the vagus, the spinal accessory, 

 and the hypoglossal. 



LITERATURE 



The occurrence of hypoglossal ganglia was first described by 

 Froriep ('82) in the sheep and the ox. He traced the develop- 

 ment of a single ganglion, anterior to the first cervical, which it 

 resembled in form, though smaller in size. The single distal 

 root of this ganglion joined the most caudad root of the hypoglos- 

 sal nerve. Anterior to this hypoglossal ganglion the neural crest 

 was undifferentiated. Froriep and Beck ('95) found a precervi- 

 cal ganglion present in the adult throughout those groups of mam- 

 mals in which the first cervical ganglion was well developed. 



Martin ('91), investigating cat embryos, found five ganglionic 

 masses posterior to the jugular ganglion, and five roots of origin 

 for the hypoglossal nerve. He concludes, therefore, that these 

 ganglia are the dorsal ganglia of the hypoglossal, though he gives 

 no figures in support of his view. 



Lewis ('03) in his excellent paper on the anatomy of a 12 mm. 

 pig found extending caudad from the jugular ganglion "a beaded 

 commissure ending in a small knob. In the track of the commis- 

 sure, but separated from it, is an irregular ganglionic mass. After 

 another interval there appears a small fragment, then follows 

 the first cervical ganglion." In one case he found a small fiber 

 bundle connecting the irregular ganglionic mass (Froriep 's 

 ganglion) with the hypoglossal nerve, but considers its "relation 

 with the commissure" as "far more striking than its resemblance 

 with a spinal ganglion." He finds the ganglion "connected with 

 the commissure in pigs of 17 mm." In a dissected pig of the same 

 length "the hypoglossal ganglion appeared as a detached part of 



