Oct. 25, 1888] 



NATURE 



629 



condemns the muscle to rest. The stimuli then start from the 

 nerve-cell, to them the muscles react by doing work, and they 

 are conveyed to the muscles through the continuation of the cell 

 which the nerve-//';? presents. \Ve need not yet trouble our- 

 selves how the excitation of the nerve-cell arises, whether 

 through external — sensory — stimuli, or through an enigmatical 

 psychic act, or through chemical influences ; certain it is that 

 these were, before the division of the nerve, the sole impulse 

 to the muscle's movements. But what the muscles lack we 

 can supply artificially, and more ; we can put the nerve-remnant 

 in such manifold states of excitement as it never before expe- 

 perienced from its cell-body, so that the muscle is compelled to 

 undergo many kinds of movement quite new to it, and we can 

 attain the same result by direct stimulation of the muscle. 



In the circle of these experiences arose the controversy, not 

 yet quite ended, 1 as to muscular irritability ; properly, the ques- 

 tion whether it was, in general, possible to stimulate anything 

 artificially that is not nerve— that is, to set free the activity 

 peculiar to a non-nervous structure by the means at our 

 command. 



Haller, who was the first to occupy himself minutely with the 

 stimulation of muscle, and introduced the term irritability, de- 

 cided, but only incidentally and by the way, that the stimulus 

 could strike also the ramifications of the nerve in the muscle, 

 and he was far from interesting himself in the question in the 

 modern sense, or from suspecting the point of view from which 

 the independent irritability of muscle would later on be ques- 

 tioned. We ought not to blame him much for the latter, since 

 even to-day it is not easy to understand the motives of an oppo- 

 sition now continued for more than a century. At the outset, 

 if I am not mistaken, the teaching of the Animistic, or, as it 

 might now be called, the Neuristic school, led to the conception 

 that not only the excitation and regulation of the various func- 

 tions, but the actual endowment of the several tissues with their 

 respective activities, was the work of that everywhere pre- 

 dominant and distinctly animal contrivance, the nervous system. 



In connection with this, there seems to have arisen the view of 

 the ubiquity of nerves — that is, of so fine a penetration of the 

 parts with nerve radiations, that, especially in muscle, not the 

 smallest particle free from nerve could be demonstrated, a view 

 which, on the strength of microscopic research, is coming up 

 again at the present day in a constantly new dress, and finds 

 energetic adherents, 2 but, as we shall see, to be refuted, espe- 

 cially by experiment. If we disregard this, we shall find the 

 tendency to consider only nerves as excitable, in some degree 

 founded on the differentiation which transferred automatism to 

 the nervous matter, robbing all the remaining tissues of irrita- 

 bility, so that they only retained the faculty of reacting to the 

 stimulated nerve with which they were bound up. This was as 

 much as saying it was impossible artificially to replace the 

 nervous stimulus, or that, if we did succeed, we were strictly 

 imitating it, in which case, indeed, we should have come un- 

 awares upon the solution of the problem of motor innervation. 

 Against such arguments it availed nothing to point out the 

 excitability of nerveless sarcode, as was often done in favour of 

 irritability ; for, just as it was formerly useless, because the real 

 genetic connection of sarcode and muscle was not known, so 

 to-day it would have to be rejected, because automatic protoplasm 

 can also be correctly considered nervous. 



A non-irritable muscle would strike us as strange enough, and, 

 against all expectation, different from the nerve, when we con- 

 sider that the nerve-fibre, although incapable of being affected 

 by all the natural stimuli which excite its ganglion-cells, free, 

 that is, from automatism, is artificially excitable at every spot 

 by the most different agents. However, we have no further 

 need of such considerations, since the question of irritability lies 

 within a region where, instead of speculation, observation and 

 experiment have become decisive. 



1 Cf. J. Rosenthal, " Allgemeine Physiologie der Muskeln und Nerven," 

 Leipzig^ 1877, p. 255. 



- T. Gerlach, " Ueber des Verhalten der Nerven in den quergestreiften 

 Muskelfaden der Wirbelthiere," Erlangen Phys. Med. Soc. Sitzber., 

 1873. "Das Verhaltniss der Nerven zu den willkiirlichen Muskeln der 

 Wirbelthiere," Leipzig, 1874. "Ueber das Verhaltniss der nervosen und 

 contraktilen Substanz der quergestreiften Muskels," Archiv Mikrosk. 

 Altai., voL xiii. p. 399. A. Foettinger, " Sur les terminaisons des nerfs 

 dans les muscles des insectes," Archives de Biol., vol. i., 1880. Engelmann, 

 Pfli'ger Archiv, vol. vii , 1873, P- 47 '» v °l. x '-, 1875, p. 463; vol. xxvi. 

 p. 531. In these publications it is sought to prove that the motor nerves 

 pass either into the interstitial nucleated substance of the muscle (therefore 

 into the sarcoglia) or into the layers of the " Nebenscheiben." This latter 

 view is opposed by, among others, A. Rollett, in his thoroughgoing expo- 

 sition of the structure of muscle (Vienna, Denkschriften der k. Akid., vol. 

 xlix. p. 29), and W. Kiihne (Zeitschr. f. Biol., vol. xxiii. p. 1. 



As a matter of fact, the older statements, long considered a 

 good basis for opposing irritability, are incorrect, as, for instance, 

 that an excised piece of muscle in which no nerves could be seen 

 with the lens did not twitch on stimulating it. 



We can show you a little piece, 3 millimetres long, from the 

 end of the sartorius muscle of the frog, in which the best 

 microscope discovers no traces of nerves, easily made recogniz- 

 able by osmium-gold staining (Fig. 1). Such a piece, trans- 

 versely cut off, twitches, as we know, at each effective muscular 

 stimulus. Pieces which can be obtained free from nerves from 

 many other muscles behave in the same way, as, for instance, 

 pieces from the delicate muscles of the pectoral skin of a frog 

 (Fig. 2). 



Further, the assertion was incorrect that everything that ex- 

 cited the nerve made the muscle twitch, and vice versa ; for we 

 see here a sartorius suspended in ammonia vapour, contracting 



Fig. 1. 1 Fig. 2. 



powerfully, while a nerve entirely submerged in liquid ammonia 

 appears wholly unstimulated, for it does not rouse the thigh 

 muscles from their repose. 



Conversely, we see a thigh whose nerve dips into glycerine in 

 maximal contraction, and, on the other hand, a muscle in con- 

 tact at its excitable end with the same glycerine remains at rest, 

 yet it twitches if I dip it in up to its nerve-bearing tracts. 2 



These are old experiments, 3 and it is admitted they have over- 

 thrown the earlier opinion. But they have not been deemed 

 sufficient to prove muscular irritability, because the ultimate 

 endings of the nerves might have an irritability other than that 

 of their stems. This is the only objection still raised. One 

 could wish no other were conceivable, for this one admits of 

 refutation. 



(To be continued.) 



D 



THE HEMENWA Y EXPEDITION IN 

 ARIZONA.* 



R. JACOB L. WORTMAN, of the United States Army 

 Medical Museum, has just returned from Arizona, where 

 he has spent the winter and spring attached to the Hemenway 

 South- Western Archaeological Expedition under the direction of 

 Frank Hamilton Cushing, which was mentioned in the March 

 number of the Naturalist, and he confirms the importance as 

 well as the genuineness of the discoveries of Mr. Cushing. The 

 Expedition is thoroughly equipped and well organized, and its 

 investigations have been conducted in a vigorous and scientific 

 manner, with special reference to the many details which go to 

 make collections of this character of value to the scientific 

 student. Not only have the ruins been carefully surveyed and 

 mapped, but each specimen has been labelled with great care, in 



1 The drawings, Figs. X. 2, 3, 5, 8, are taken from the papers of Dr. K. 

 Mays, " Histophysiologische Untersuchungen iiber die Verbreitung der 

 Nerven in den Muskeln" (Zeitschr. Biol., vol. xx. p. 449), and "Ueber 

 Nervenfasertheilungen in den Nervenstammen der Froschmuskeln " 

 (Zeitschr. Biol., vol. xxii. p. 354); Figs. 9-13 are from the author's papers 

 in Zeitschr. Biol., vol. xxiii. pp. 1-148, Plates A-Q. 



2 The experiments were performed during the lecture by projecting on the 

 wall images of the preparations enlarged some thirty times. 



3 Kuhne, " Ueber direkte und indirekte Muskelreizung mittelst 

 chemischer Agentien," Mailer's Archiv. f. Anat., 1859, p. 213. 



* Reprinted from the American Naturalist, June 1888. The writer is 

 Mr. Thomas Wilson, of the Smithsonian Institution. 



