M. Hilaire on the Vision of the Mole. 341 



tension of the olfactory apparatus, to follow the course along 

 which it directs itself, in the other animals, to the tubercula 

 quadrigemina, follows another direction, and anastomoses with 

 the nerve of the seventh pair. 



The observation of certain monstrosities furnishes examples 

 of anomalies of precisely the same nature. 



It is a fact well known in science, that each organ of sense is 

 necessarily provided with two kinds of nervous systems, a spe- 

 cial and principal nerve, which imparts life to the apparatus, 

 and maintains it, and an accessory nerve. These nerves are, 

 for the sense of smell, the olfactory and nasal nerves ; for that 

 of sight, the optic and ophthalmic ; and for that of hearing, the 

 acoustic nerve and the branch of' the cochlea. 



The mole also possesses its two ocular nerves, the principal 

 and acces.sory, that is to say, the optic and ophthalmic. For the 

 two nervous actions attributed to these two nerves, being con- 

 trary in direction, and yet simultaneous, could not be accom- 

 phshed by a single branch. Now, in the mole, independently 

 of the nerve which occupies the bottom of the eye, and which 

 this position ought to induce us to consider as the optic nerve, 

 there is another which occupies at its commencement a point of 

 the circumference of the eyeball. This latter seems to come 

 from a mucous or glandular tissue; or, perhaps, it even issues 

 from a true lacrymal gland. The two nerves of the eye of the 

 mole are inclosed in a common sheath, in the same neuri- 

 lema. 



Colours zohich (liferent Substances communicate to the Flame of 

 the Blowpipe. By M. Buzrngeiger. 



I USE a lamp constructed after the model indicated by Berze- 

 lius in his Treatise on the Blowpipe. It is of great importance 

 that one .see in a distinct manner the conical blue flame, and the 

 tran.sparent blue vapour which envelopes and terminates it. I 

 produce this effect by cutting tlu> wick obliquely, the highest 

 part being to the right, and opening it longitudinally, in or- 

 der to introduce the point of the blowpipe. I made use of 



