Jakuaby 28, 1910] 



SCIENCE- 



149 



eral course and distribution. The conclusions 

 derived from these facts may be modified by 

 the embryonic or the phylogenetic history, 

 which may give evidence that the nerve has 

 reached its observed adult position through 

 secondary shifting or change of course. The 

 point of view is illustrated in the recognition 

 of the ophthalmicus profundus as a separate 

 segmental nerve in spite of its central origin 

 in common with the trigeminus in every verte- 

 brate. Also, in the shifting of the roots of 

 several cranial nerves from segment to seg- 

 ment. Also, in the analysis of the vagus into 

 several segmental nerves because of its periph- 

 eral relations. Also, in the recognition of a 

 general cutaneous component in each seg- 

 mental nerve, including the facialis, although 

 all these components are commingled in a non- 

 segmental central nucleus. The statement 

 made by Allis expresses a profound but not 

 uncommon misconception of the attitude and 

 method of students of nerve components. 

 Without exception these workers would agree 

 with Allis in attaching primary importance to 

 the peripheral course and distribution of 

 nerves, but they would not agree that this is 

 in any way inconsistent with the neurone 

 theory. 



What has led Allis to the statement quoted 

 above is the fact that communis fibers have 

 not been recognized as a primary component 

 of the trigeminus as a segmental nerve. He 

 argues in substance as follows: in some fishes 

 communis fibers are distributed by way of the 

 rami of the trigeminus and, generally, cu- 

 taneous fibers run in the hyoideo-mandibular 

 ramus of the facialis. In Amia and Petro- 

 myzon cutaneous fibers are present in the root 

 of the facialis. Why should not both com- 

 munis and cutaneous components be assigned 

 to both trigeminus and facialis ? Students of 

 nerve components have assigned the communis 

 fibers to the facialis and the cutaneous fibers 

 to the trigeminus, except where they run in 

 the root of the facialis, on phylogenetic 

 grounds. In forms not provided with an 

 operculum the cutaneous component in the 

 hyoid segment is primitive and has its root 

 and its ganglion cells in the facialis root and 



ganglion. In operculated forms (with the 

 single exception of Amia so far as known) 

 this cutaneous component in the facialis has 

 disappeared and fibers from the trigeminus 

 have secondarily invaded facialis territory to 

 supply the operculum. 



Similarly, in primitive forms no communis 

 fibers have been found in the trigeminus. In 

 fishes in which taste organs are present in the 

 outer skin of the head, such fibers are distrib- 

 uted by way of the trigeminal rami, but they 

 leave the brain in the facialis root and have 

 their ganglion cells in the facialis ganglion. 

 Their distribution is therefore secondary and 

 they belong to the facialis segment. The same 

 is true of the facialis root fibers which go to 

 the fins, or even the tail, to supply taste buds. 



It is one advantage of the neurone theory 

 that such cases as this are explained without 

 difficulty, while upon the Hensen hypothesis of 

 primary continuity of nerve cell and end 

 organ, it is inconceivable how taste organs in 

 the skin should have secured a nerve supply 

 at all, since the taste organs in primitive forms 

 were wholly entodermal and the cutaneous 

 nerves did not carry any fibers to innervate 

 them. J. B. Johnston 



SCIENTIFIC JOURNALS AND ARTICLES 

 The Journal of Biological Chemistry, Vol. 

 VII., No. 2, issued January 8, 1910, contains 

 the following: "Effects of the Presence of 

 Carbohydrates upon the Artificial Digestion 

 of Casein," by N. E. Goldthwaite. The diges- 

 tion of casein is retarded by the presence of 

 carbohydrates. " The Quantitative Separation 

 of Calcium and Magnesium in the Presence 

 of Phosphates and Small Amounts of Iron 

 Devised Especially for the Analysis of Foods, 

 Urine and Feces," by Francis H. McCrudden. 

 Description of a new method. " A Note on 

 the Estimation of Total Sulphur in Urine," 

 by Stanley R. Benedict. Criticism of Eitson's 

 method. " The Fate of Sodium Benzoate in the 

 Human Organism," by H. D. Dakin. Daily 

 doses of 5 to 10 grams of sodium benzoate for 

 two or three days are eliminated practically 

 quantitatively in the urine as hippuric acid. 



