22 



'NATURE 



[May 6, 1897 



Greenland is milder than that of Baffin's land, partly owing to a 

 warm current which skirts the land northward as far as Melville 

 Bay, and partly owing to a difference in the prevalent winds. 

 Greenland is being depressed, probably owing to an accumulation 

 of ice, which is now being taken off from the glaciers where 

 they enter the sea. The American side is rising north of 

 Labrador. — Temperature and ohmic resistance of gases during 

 the oscillatory electric discharge, by J. Trowbridge and T. W. 

 Richards. Although a vacuum tube will offer a resistance of 

 several thousand ohms to a continuous discharge, its resistance to 

 an oscillatory discharge may not exceed ten or twenty ohms, as 

 shown by the feeble damping impressed upon the discharge. 

 The latter is determined by spark photographs, and by finding 

 what wire resistance will produce the same amount of damping. — 

 Does a vacuum conduct electricity? by John Trowbridge. It 

 does. — The affinities of Hesperornis, by O. C. Marsh. Points 

 out that his characterisation of Hesperornis as a "swimming 

 ostrich" in 1872, has since been verified (see Nature, vol. Iv. 

 P- 534). 



SOCIETIES AND ACADEMIES, 

 London. 



Royal Society, April 8. — " Double (Antidrome) Conduction 

 in the Central Nervous System." By C. S. Sherrington, M.A., 

 M.D. , F. R.S., Holt Professor of Physiology, University College, 

 Liverpool. Received Februaiy 15, 



In a paper presented to the Society last year, I drew attention 

 to the fact that if, after transection over the bulbospinal axis, the 

 funiculus gracilis be excited, at the calamus scriptorius, the 

 excitation evokes movement (contraction, relaxation) in the 

 idiolateral hind limb. If instead of f. gracilis the funiculus 

 cuneatus be excited, the movement (contraction, relaxation) is in 

 the idiolateral fore limb. The movement in the hind limb is in 

 the monkey usually adduction and flexion of hallux, in the cat 

 flexion of knee, hip, or ankle. In the monkey the fore limb 

 movement is usually flexion and adduction of pollex, often with 

 extension of the other digits ; in the cat, more usually flexion of 

 elbow with protraction of the shoulder. The movements which 

 occur are, however, various, and I will here only add that those 

 from the f. gracilis include the vaginal and anal orifices, the tail, 

 and the abdominal muscles, those from f. cuneatus the dia- 

 phragm ; but that neither fromy. gracilis nor f. cuneatus have 

 I obtained idiolateral extension of elbow or of knee. 



The reaction is obtainable when the transection has been 

 made altogether below the nuclei graciles et cuneati. It 

 therefore does not necessarily involve the cells of those 

 nuclei. 



The reaction from the left f. gracilis is annulled by severance 

 of the left dorsal column, that of the right by the severance of 

 the right. 



What, then, is the nature of this reaction obtainable from the 

 /. graciles and cuneati ? The reaction is evidently one which 

 involves each dorsal column of the cord as a conducting path, in 

 many cases even employing its whole length. In light of the 

 evidence given above, I infer that although certainly, as has 

 been long established, the dorsal column is, with the single 

 exception of its short, scanty, and deeply-placed groand-bundle, 

 a functionally pure upward path, consisting of nothing else than 

 sensory root fibres, the vast majority of which— and the entirety 

 of the longest of which — are ascendant ; the conduction along it 

 in these experiments is downward, even extending its whole 

 length. That is to say, the conduction must be downward and 

 cellulipetal along ascending axons which function in a cellulifugal 

 direction ; that is to say, the propagation of the impulses arti- 

 ficially started in my observations must have been antidrome 

 instead of orthodronie. The motor discharges evoked I refer to 

 the spread of the excited condition into the collaterals of the 

 axons excited to antidrome conduction, their collaterals im- 

 pinging upon motor neurons. 



The direction of propagation occurs therefore in opposition 

 to the law of the '■'^ polarisation dynamique des nevrons " put 

 forward by Ramon y-Cajal and V. Gehuchten. It offers, how- 

 ever, no contradiction to what James has termed " the law of 

 forward direction " ; it only emphasises that that law predicates 

 the existence of at least two links in its conduction-gear. 



The reaction is therefore, in my view, an extreme illustration 

 of double (antidrome, doppelsinnige) nervous conduction. After 



NO. 1436, VOL. 56] 



du Bois' fundamental observation with frog's sciatic and the 

 electrical sign, it has been Kuhne's sartorius experiment, and 

 Babuchin's reversed discharge in the electric organ nerve-fibre, 

 which have laid a satisfactory foundation for double conduction 

 in peripheral nerves. But between those experiments and these, 

 the subject of this note, there are, it is true, differences. In the 

 latter, (o) propagation occurs over relatively huge distances and 

 (;8) the reaction occurs within the field of the central nervous 

 system. These differences need not, however, negative the 

 relationship of the phenomena. They render it the more 

 instructive. 



It is obvious that there must be opportunity for detection of 

 antidrome conduction in parts of the central nervous system 

 besides the dorsal spinal columns. Thus, on exciting, especially 

 with electric currents, the mammalian metencephalon {vermis 

 cerebelli) and isthmus rhombencephali, subsequent to ablation 

 of the parts above, I have seen movements produced in the limbs 

 and trunk, and also inhibitions occur. Thus, in instance of the 

 latter, inhibition of the tonic extensor spasm of the fore and 

 hind limbs combined with contraction of the flexors of knee and 

 elbow, such as is seen under local spinal reflex action. It will 

 have to be determined whether in such cases as the former we 

 have not before us instances of antidrome conduction along 

 ascending paths. The antidrome phenomenon, while of valu- 

 able assistance when recognised, may, if unrecognised, give 

 rise to very misleading inferences. Its methodic use should 

 place in our hands a fresh instrument of value for neurological 

 research. 



" On the Breaking-up of Fat in the Alimentary Canal under 

 Normal Circumstances and in the Absence of the Pancreas." 

 By Vaughan Harley, M.D., M.R.C.P., Professor of Patho- 

 logical Chemistry, University College, London. Received 

 March 18. 



In this paper the author, after stating the results of his pre- 

 vious experiments, in which he found that from 21 to 46 per 

 cent, of the total fat given in a milk diet was absorbed from the 

 alimentary canal in the space of seven hours in normal dogs, 

 found that in those dogs in which the pancreas had been 

 entirely removed two days previously, no evidence of any absorp- 

 tion could be obtained during the same time. 



The fact that no marked absorption of fat occurred in 

 dogs after the extirpation of the pancreas, seems to confiim 

 the old view that the pancreatic secretion was necessary for 

 absorption. 



This alleged action of the pancreatic juice in preparing fat for 

 its absorption, is usually supposed to be due to the fat-splitting 

 ferment and the alkaline sodium carbonate, which combines to 

 form soaps with the free fatty acids. 



In the author's paper he investigated whether, after the 

 removal of the pancreas, fat continued to be broken up in the 

 alimentary canal. For this purpose animals were fed on milk, 

 and seven hours later the contents of the stomach, small intes- 

 tines, and large intestines were separately analysed with regard 

 to the quantity of neutral fat, free fat acids, and fat acids as 

 soaps. 



As far as the stomach is concerned, the quantity of fat acids 

 was increased in the dogs in which the pancreas had been 

 removed. It seems that this increase is probably due not to a 

 greater splitting-up action of the fat, but to the longer retention 

 of the fat in the stomach ; for after the pancreas is removed, the 

 motility of the stomach is much diminished. 



Soaps also were formed both in the normal and pathological 

 dogs, so that both in the normal dogs as well as in those in 

 which the pancreas had been removed, the stomach is capable 

 not only of splitting up neutral fat into free fat acids and 

 glycerine, but that, further, they are capable of finding an 

 alkaline substance with which they can form soaps even in the 

 acid stomach contents. 



The power of the free fafty acids for forming soaps is, how- 

 ever, extremely limited in the stomach. In normal dogs the 

 principal fat- splitting action really begins not in the stomach, 

 but after it has left the pylorus. 



The normal dogs contain no less than 72-22 per cent, of the 

 total fat as free fat acids, while, when the pancreas had been 

 entirely removed, no less than 61 "62 per cent, of the total fat 

 was thus present. There can be no doubt, therefore, that even 

 where no pancreatic secretion has reached the intestines, a very 

 considerable quantity of neutral fat is split up into free fat acids 

 in the small intestine, although the quantity there formed is not 



