Huber-DeWitt, Nerve-Endings in Muscles. 189 



that is common in appearance with them, we think, after every 

 allowance has been made for visual error, that they may be con- 

 sidered bipolar cells situated in the path of the fibers, and that 

 the end apparatus should be looked upon as their terminal ex- 

 pansion. However the number so far seen is too few to enable 

 us to regard them from other than a somewhat hypothetical 

 standpoint." As our observations were ma'de on the cat and 

 more particularly on the auricle, we are not fully prepared to 

 discuss Berkley's results. We may however be allowed the fol- 

 lowing critical remarks : In the first place, in the cat at least, 

 as our figures may show, the ultimate nerve endings in the 

 heart muscle can not be divided into two distinct types — simple 

 and complex ; intermediate stages of complexity are found be- 

 tween these two extremes. Furthermore the endings described 

 by us are all endings of varicose fibers, which, it is true, may 

 not always show the same degree of varicosity ; yet this differ- 

 ence is not regarded as of any essential importance, as we have 

 above stated. The suggestion may further be made, as has 

 been done by one of us in another place, that the nodular en- 

 largements, which Berkely has interpreted as the cell bodies of 

 bipolar cells, may, after all, be nuclei of the sheath of Schwann 

 of non-medullated and not medullated fibers. When we com- 

 pare the size of the nodular enlargements pictured by Berkley 

 with the size of some of the nuclei found on non-medullated 

 fibers, stained in methylene blue' and counter-stained in alum 

 carmine, when viewed under about the same magnification, we 

 are led to disagree with him when he states that "this swelling 

 in the pathway of the nerve is far too large to be thought of as 

 a varicosity or as the nucleus of the myelin sheath of the nerve 

 fiber, supposing such a sheath to occur in this situation." 



These considerations make us somewhat skeptical as to the 

 existence of two distinct kinds of nerve fibers with characteristic 

 end-apparatus; and while we have no desire to discredit Berk- 

 ley's observations in this direction, we can but feel that 

 methods other than the chrome-silver method where the struc- 

 ture of the fiber, etc., may be determined with greater certainty, 

 are more suitable for the investigation of this problem. 



