ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 767 



" glands " themselves. He concludes that this acid fluid is of no use 

 to the animal when once secreted, and he again directs attention to 

 the peculiar structure of the so-called glandular organs, which much 

 need a thorough re-examination. 



Olfactory Organ of Parmacella.* — H. Simroth, dealing with the 

 olfactory organ of this terrestrial pulmonate gasteropod, and with 

 the question whether there is any relation between the olfactory sense 

 and respiration, points out that the pulmonary tissue is extremely well 

 developed, and that from the anterior edge of the respiratory space 

 there extends into the mantle-cavity a shallow groove, bounded by 

 two distinct ridges ; these are in length at least equal to that of the 

 transverse diameter of the body, they are richly provided with 

 ganglion-cells, and traversed by bundles of muscular fibres. There 

 can, then, be no doubt that we have here a sensory organ, and that 

 that organ is olfactory in function. 



Another question which arises is as to the homology of this part 

 with the olfactory organ of aquatic gasteropods. The position and 

 mode of innervation of the organ makes this very doubtful, and, taken 

 in conjunction with the systematic position and life-history of the 

 possessor, leads us to think that we have here to do with a recently 

 acquired structure. 



Innervation of the Mantle of Lamellibranchs.f — L. Vialleton 

 has studied Unio and Anodonta by removing the mantle from its 

 attachments in a living specimen, and placing it for 15 minutes in 

 lemon juice, and then for about 20 in a 1 per cent, solution of 

 chloride of gold. Feebly acidulated water is added, and, after 24-36 

 hours' maceration, the examination may be entered upon. In the 

 portion of the mantle situated within the pallial impression, the 

 nerves are found to be especially distributed along its two faces, a 

 little below the epithelium; from their mode of union there result 

 nodal points of varying form, and a plexus presenting spaces differing 

 in shape and size ; from each superficial plexus there are given off 

 finer fibres, which either arise directly from larger nerves or from the 

 fiuer branches of them ; they finally divide into ultimate fibrils 

 which form a closely-set subepithelial plexus. The whole arrange- 

 ment may be compared to that which is found in the connective tissue 

 of the cornea of the human eye. Observations on allied forms lead 

 the author to believe that this arrangement is common to all Lamelli- 

 branchs. 



Differentiation of Protoplasm in Nerve-fibres of Unionidse.J — 

 In investigating this subject, J. Chatin, after treating with osmic 

 acid, teases the nerve-fibres of Unio pidorum, Anodonta cygnea, &c, 

 stains with carmine or anilin red, and mounts in glycerine. The axis 

 of the fibre consists of a bundle of fibrils longitudinally arranged; 

 around this bundle lies a protoplasmic layer containing nuclei here 

 and there, but difficult to observe. The protoplasm is finely granular ; 



* Zool. Auzeig., v. (18S2) pp. 473-5. 



t Comptes Rendus, xciv. (1882) pp. 461-3. 



X Ibid., pp. 1723-6. 



3 f 2 



