174 REPORT — 1859. 



busily upon each other. The sound was never heard except when this act was 

 being performed, aod at the time it was heard no other of the creatures was even 

 seen engaged in anv particular manner nor placed in any special or constant position, 

 though they were repeatedly and carefully watched. When examined with a 

 pocket lens, and with a low power of the compound microscope, the part of the 

 Notonecta's legs, of which it made use at the time of the production of the sound, 

 was seen to be covered with stiff hairs or other projections of its external covering. 

 Further examination of the part was delayed until other specimens could be secured, 

 and during this time the original was unfortunately lost. Yet notwithstanding that 

 the examination was less complete than might have been wished, the opportunities 

 of examining the action of the animal at the time it produced the sound were so 

 numerous, that there can be no doubt that the noise was caused by rubbing the 

 fore-legs together, a method which seems either very rare amongst insects, or to 

 have been but rarely observed and recorded. 



On the Admixture of Nei-vous and Muscular Fibres in the Nerves of the 

 Hirudo Medicinalis and other Leeches. By Peter Redfern, M.D. Lond., 

 F.R.C.S.L. 



The author stated that very remarkable movements take place in the nerves of 

 leeches after removal from the body, and that though they had been known to him 

 since October 1847, when they were shown to him by Dr. Mandl, he believed that 

 their existence is yet but little known. These movements have been demonstrated 

 in the class of Histology in the University, and King's College, Aberdeen, for the 

 past twelve years ; the author informed Professor Goodsir of them in 1848, and 

 showed them to Professor Paget's class at St. Bartholomew's Hospital in 1855. 

 Mayer states that Hannover first observed them. Remak ascribed them to the con- 

 traction of muscular fibres within the nerve-sheath. Leuckart and Will have 

 observed similar phenomena in the nerves of insects and Naiads. 



The author pointed out that the best method of showing these movements is to 

 remove one or more of the ganglia and their branches from the gangliated cord of 

 the leech, to dissect away the sheath very carefully with needles, so as to leave the 

 ganglia and nerves perfectly bare and free from all adhering muscular fibres. On 

 waiting for a short time, slow but very decided oscillatory movements of some of 

 the nerve-trunks may be observed in almost every instance examined. These move- 

 ments take place quite indifferently in the large cords connecting the ganglia, and in 

 their gangliated and non -gangliated branches. The action of water elevates the 

 neurilemma of the nerves into vesicles, and shows the cause of the oscillatory move- 

 ments. The attention should be directed to the concave side of any of the branches 

 of nerve which are curled, or to both sides of nerves which are oscillating ; and one 

 or more muscular fibres of the ordinary characters of the fibres of the leech may 

 be seen in every moving nerve at one period or other of the action of the water. 

 When the movement is compared with that which maybe seen in ordinary muscular 

 fibres of the leech when stimulated by the contact of water, the character of the 

 two movements is found to be identical. The author has not seen movements con- 

 tinue for more than a few minutes in the dissected muscular fibres, but he has 

 repeatedly watched them for half an hour, several times for 50 minutes, and once 

 for 70 minutes, in the nerves of the leech. He gave no opinion on the purposes 

 served by this peculiar mixture of nervous and muscular elements, where nervous 

 elements alone were formerly supposed to exist, but expressed a desire that the 

 members of the Association would make the occurrence more generally known, that, 

 by the labours of a number of physiologists engaged in the examination of different 

 animals, it may be determined to what extent in the animal kingdom these so-called 

 elementary tissues are mingled, with the view of arriving at some plausible conjec- 

 ture as to'the nature of the end gained by such an arrangement. 



On the Structure of the Otoliths of the Cod (Gadus Morrhua). 

 By Peter Redfern, M.D. 

 From examination of the otoliths of the cod, haddock, flounder, salmon, and 



