94 The American Naturalist. [January, 
of organic matter. It has, moreover, been suggested by Langley! 
that we must assume a third kind of fibre, which he calls ‘‘ anabolic,” 
to account for the formation of fresh substance in the gland cells. 
More recently, however, Langley? has studied the effect of atropin on 
the chorda tympani, and has obtained results which throw doubt on his 
own and Heidenhain’s views. These results he sums up as follows :— 
‘ The various changes caused in the gland cells by nerve stimulation 
are all affected by atropin, and to approximately equal extents. 
paralysis of the chorda occurs, it is a paralysis of the whole of its 
function with regard to the gland cells. In other words the 
phenomena of atropin poisoning give us indication of the existence 
of more than one kind of secretory nerve fibre in the chorda 
tympani.” It should be observed that this last sentence puts the 
case too strongly. Langley’s experiments indicate that the trophic 
and anabolic fibres may in some cases be paralyzed more completely 
than the secretory, though the degree of difference is slight ; and the 
existence of the three kinds of fibres cannot yet be regarded as abso- 
lutely disproved. 
Bayliss and Bradford,’ who have worked on the electrical phenomena 
of the submaxillary gland, assert that stimulation of thesecretory fibres 
causes the hilus of the gland to become positive to the outer surface, 
and stimulation of the trophic fibres makes the outer surface positive to 
tne hilus. Since the first current is abolished by atropin sooner than 
the second, the presumption is that the secretory fibres are paralyzed 
sooner than the trophic. Langley, however, thinks that the two cur- 
rents are due to the preponderance of, first, physical, and second, 
chemical changes in the gland cells, and that therefore the electrical 
phenomena are not incompatible with his results—Mary A. JoHN- 
SON. 
Secretion of Salts in Saliva.—The power of choice exercised 
by a gland in the selection of substances offered it by the blood is lit- 
tle understood. Novi‘ brings forward facts that bear in a general way 
upon this point in studying the chlorine (7.¢., NaCI) contents of the 
submaxillary saliva of the dog. He finds this to vary with two fac- 
tors, viz.: the rate of secretion, and the amount of, NaCl present in — 
the blood. If the latter remain the same, increasing the rate of secre- 
1 Journal of Physiology, Vol. V1. p. 88. 
2? Journal of Physiology, Vol. IX., p. 55. 
3 Proc. Roy. Soc., Vol. XL., p. 203, 1886. 
* Du Bois Reymond’s Archiv., 1888, p. 403. 


