84 Journal of Comparative Neurology. 



incubation, and by KolHker (i8) on rabbit embryos i6 days old 

 they having shown that the ciliary, the spheno-palatine and otic 

 ganglia have their ««/^^r in cells which "bud out" from the 

 Gasserian ganglia. 



In this brief sketch I have endeavored to show that the 

 evidence is in favor of the supposition that the sympathetic 

 ganglia of the great chains and those found on the cranial 

 nerves, are developed from germ cells which wander out from 

 the anlagen of the spinal ganglia and from the anlagen of 

 the sensory ganglia on the cranial nerves. These cells are 

 at first apolar and proliferate by karyokinetic cell division. 

 The clusters of cells which form the beginning of the ganglionic 

 chains are centers from whence germ cells wander to organs and 

 tissues to form the milagen of the sympathetic ganglia there 

 found. As development proceeds, the apolar germ cells de- 

 velop into sympathetic neurons by a budding out of the neur- 

 axes and of the dendrites, this differentiation or further devel- 

 opment being essentially the same as that described for the 

 germ cells or neuroblasts found in the developing neural canal, 

 which, as I have above stated, develop into the motor and 

 intra-medullajy neurons. 



Shape ayid sinicturc of neurons of tJu sympatJietic system. — 

 The neurons of the sympathetic system are usually found in 

 larger or smaller groups, forming the so-called sympathetic 

 ganglia. These ganglia vary greatly in size. Many attain di- 

 mensions great enough to make their recognition very easy, as 

 for instance, the superior cervical ganglion, which in man is 

 about 20 mm. long and 4 to 6 mm. broad (Quain). From 

 ganglia of such size, every gradation in size is met with until the 

 microscopic ganglia — the terminal ganglia — found in the vari- 

 ous organs are reached. All sympathetic ganglia, large and 

 small, are invested with a connective tissue capsule, which is 

 continuous with the perineural sheath of the nerves entering 

 and leaving the ganglion. In a general way it may be stated 

 that the thickness of the capsule is proportionate to the size of 

 the ganglion. From the capsule, connective tissue trabeculae, 



