Journal of Applied Microscopy. 445 



disposed of, since it increases in size during the greatest growth periods, and is 

 removed before mitosis. He does not consider it important as a nutritive or 

 circulatory element. a. m. c. 



The author reviews the work of older 

 Alcock, R. The Peripheral Distribution of the ^ . ^ ^i . . . j ^ i 



Cranial Nerves of AmmoccEtes. Journ. of anatomists on this question and takes 

 Anat. and Phys. 33 : N. S. 13, 131-153, i pi- as special points for study: 1. The 

 ^ ■ innervation of the tentacles round the 



mouth. 2. The innervation of the epithelial pit sense organs on the head and 

 bronchial region of the body. 3. The peripheral distribution of the facial nerve 

 which has been said to be purely sensory. 4. The innervation of the thyroid 

 and of the bronchial muscles. 5. The destination of the lateral line branch of 

 the vagus and the recurrens facialis. 6. The limits of the vagus in the alimen- 

 tary canal. 7. The existence of a sympathetic system. In this paper the dis- 

 tribution of the bronchial, facial, glosso-pharyngeal and vagus, and the arrange- 

 ment and innervation of the sensory epithelial pits of the head and bronchial 

 region of the body are alone considered, the remaining points being left for a 

 future contribution. 



The distribution of nerves was followed by means of serial sections stained 

 variously but most successfully with picro-carmine. The nerves being all non- 

 meduUated made osmic acid useless for differentiation. Nigrosin, hsematoxylin, 

 borax-carmine, and osmic acid were all tried with varying results. Picro-carmine 

 gives a deep red color to the outer sheath and nuclei, and a yellowish tinge to 

 the axis cylinders of the fiber. Difficulties were introduced by the action of 

 picro-carmine on the outer skin layer, prolonged immersion of the animal for 

 several days at a temperature of 60 degrees C. caused the disappearance of this 

 layer by solution, and too short an action made it become very hard and granu- 

 lar and difficult to cut. Motor and sensory fibers may be readily distinguished in 

 spinal nerves by their difference in size, but in the cranial nerves all fibers are 

 extremely small, and distinction by size is impossible. 



Briefly summarizing the results, the author finds : That each bronchial nerve 

 is entirely confined to its own segment as far as the motor and sensory nerves are 

 concerned ; there is no ramus praetrematicus nor ramus postrematicus. Each bron- 

 chial nerve consists of motor nerves to the striated muscles of a segment ; sen- 

 sory nerves to the diaphragm, and dorsal and ventral nerves to the lateral line 

 sense organs. The facial has all the components of a typical bronchial nerve 

 and hence belongs to the glosso-pharyngeal and vagus group of cranial nerves 

 and not to the trigeminal. The thyroid gland is innervated by a branch of the 

 facial, and therefore belongs to the hyoid segment. The facial gives off a branch 

 to all the tubular muscles in the bronchial segments. The sense organs of the 

 lateral line system on the head and bronchial region are innervated by dorsal 

 and ventral branches of the facial, the glosso-pharyngeal and the six bronchial 

 divisions of the vagus. The lateral line sense organs posterior to the bronchial 

 region of the body are innervated by the lateral line branch of the vagus. 



A. M. c. 



