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tinuous with the fibrous tissue of the tendon; when the ending is 

 intrafascicular, they are continuous with the intramuscular fibrous 

 tissue 1 ). 



The nerve -ending lies either, near the centre of the muscle-fibre 

 or near one extremity. I have found the distance from the nerve- 

 ending to one extremity of the fibre as much as five to six times 

 greater than the distance to the other extremity. Doubtless still greater 

 differences exist. Very rarely in mammalian muscles two nerve-endings 

 may be found near one another on the same muscle -fibre. I have 

 examined hundreds of fibres without finding an instance where the 

 same fibre had two nerve -endings separated from one another by a 

 considerable distance. 



In the M. obliquus abdominis ex tern us of the rodent most 

 of the fibres going to make up the primary segments run from one 

 transverse tendon to another, terminating by an intratendinous ending 

 at each extremity, and the nerve-ending lies in the middle two-fourths 

 of the fibre. The fibres making up those portions of the muscle where 

 the transverse tendons are not well developed most of them end at 

 one extremity, or at both, by an intrafascicular termination. The 

 region of innervation of the individual fibres here varies greatly, being 

 sometimes near the middle of the fibre, sometimes near one extremity. 

 The general internal structure and mode of innervation here resembles 

 greatly that of the whole external oblique muscle in certain of the 

 larger mammals. We may therefore now turn to consideration of this 

 latter subject. 



In each of the larger mammals which I have examined, cat, dog, 

 pig and man, the structure of the M. obliquus abdominis ex- 

 tern us is essentially the same, though varying in certain minor 

 respects. 



Fig. 3 represents a specimen of this muscle removed from a 

 human body. The muscle is too thick to permit of the use of osmic 

 acid on the muscle as a whole. The nerves have therefore been dis- 

 sected out after a slight maceration of the specimen. Only the larger 

 trunks are shown in the figure because no complete dissection could 

 be made of all the finer branches visible under low power of the micro- 

 scope. As a rule in man lateral branches of the (5th) 6th, 7th, and 

 8th intercostal nerves send out muscle -branches, the main trunks of 



1) The elastic tissue aiding in the union of each muscle -fibre to 

 the skeletal framework of the muscle, is removed by the method here 

 employed. It is described by Kahn, Arch. f. mikr. Anat., Bd. 57, 1901. 



