Miscellaneous. 75 



current along a jiortion of a motor nerve so alters the molecular 

 state of that nerve as to render it incapable of exciting contraction 

 when irritated. 



These facts, even without those equally important though less 

 thoroughly understood experiments of Ludwig and Bernard, which 

 appear to indicate a direct relation between nerve-force and 

 chemical change, seem sufficient to prove that nerve-force must 

 henceforward take its place among the other physical forces. 



This then is the present state of our knowledge of the structure 

 and fimctions of nerve. We have reason to believe in the existence 

 of a nervous force, which is as much the property of nerve as mag- 

 netism is of certain ores of iron ; the velocity of that force is 

 measured ; its laws are, to a certain extent, elucidated ; the struc- 

 ture of the apparatus through which it works promises soon to be 

 unravelled ; the directions for future inquiry are limited and marked 

 out ; thus the solution of all problems connected with it is only a 

 question of time. 



Science may be congratulated on these results. Time was, when 

 the attempt to reduce vital j)hfenomena to law and order was re- 

 garded as little less than blasphemous : but the mechanician has 

 proved that the living body obeys the mechanical laws of ordinary 

 matter ; the chemist has demonstrated that the component atoms of 

 living beings are governed by- affinities, of one uature with those 

 which obtain in the rest of the universe ; and now, the physio- 

 logist, aided by the physicist, has attacked the problem of nervou.s 

 action— the most especially vital of all vital phsenomena — with 

 what result has been seen. And thus from the region of disorderly 

 mystery, which is the domain of ignorance, another vast province 

 has been added to science, the realm of orderly mystery. 



MISCELLANEOUS. 



On the Saliva o/Dolium galea. By Professor Troschel. 



Statements have recently been made tending to prove that the 

 boring Mollusca penetrate stones by a purely mechanical action. 

 The following observations of Professor Troschel seem to show that 

 in some cases the perforating action of Mollusca may be due to a 

 chemical cause. 



In the ' Voyage of the Astrolabe,' Quoy and Gaimard state that 

 the DoHutn galea, a Ctenobranchous mollusk nearly allied to the 

 Buccini, possesses salivary glands of extraordinary development. 

 They are composed of two lobes, of which the anterior alone is 

 glandular ; the posterior forming a sort of pouch which attains the 

 size of a pigeon's egg, and contains an aqueous liquid mixed with 

 bubbles of air. The efferent canal of the gland passes through the 

 nervous ring which surrounds the oesophagus and opens into the 

 buccal cavity in front of the tongue. 



