156 ELECTRO-PHYSIOLOGY CHAP. 



which appear in different forms of muscular contraction. 

 Bowman first made observations on these muscles, and his 

 results tally exactly with the preceding. Here we find an un- 

 dulatory contraction in the individual, living or surviving, 

 muscle-fibres, which may be directly observed with the micro- 

 scope, and thus (as also from the excessive slowness of the 

 process) exhibit minutia? that must always escape us in the 

 entire muscle, where we have numerous fibres in very different 

 physiological conditions. It is further possible to fix such short 

 contractions during their course, by treatment with proper 

 methods of hardening, so that the finest details of the changes 

 which accompany the process of contraction in the muscle-fibres 

 become visible. Even during life two processes of movement 

 may be observed in the striated muscles of many insects, those 

 which corresponding with the twitch of vertebrate muscles con- 

 sist in the rapid, instantaneous contraction of the muscle-bundle 

 in Mo, and, on the other hand, knots or short waves spreading 

 slowly over the fibres, which often arise periodically or rhythmic- 

 ally with no demonstrable external stimulus. Here again it is 

 important to note that, as Wagener (17) pointed out with regard 

 to the larva of Corethra, the fibres in which this wave-action is 

 apparent were perfectly capable of producing total contractions 

 (twitches). He repeatedly saw both forms of movement alterna- 

 ting in the same fibre, to which, however, it must be added that 

 the wave -action does not appear in perfectly vigorous animals. 

 Laulanie (18), who investigated Corethra-larv* in every possible 

 stage of dying, also makes a sharp distinction between the muscular 

 movements of the vigorous animal and those of the surviving 

 muscles of the dying animal. He regards the former (" secousses, 

 contractions totales et simultanees ") as the expression of normal 

 muscular activity ; the latter (" ondes musculaires ") as the expres- 

 sion of intrinsic activity in the surviving muscles. Eollett (19) 

 subsequently analysed both phenomena more exactly. He 

 described the undulations of the muscles of dying Corethra-larvse 

 as follows : " The waves, at first few in number, in single fibres 

 of the muscle visible only under the microscope, gradually appear 

 in more and more of the fibres, and then repeat themselves in 

 the same fibres at ever-shorter periods, so that a lively undulation 

 ensues, which only dies away after a long time, as it came. The 

 waves in the single fibres repeat themselves only at longer periods, 



