134 SPECIAL HISTOLOGY. 



very delicate investigations, I have used only acetic acid, and have 

 arrived at the following results: — Each point of a papillse, or each 

 papilla with an axile corpuscle, generally contains two, or as frequently 

 happens at the points of the fingers four, dark-bordered tubules, which, 

 surrounded by a neurilemma^ which has escaped previous observers, 

 pass upwards through the axis of the papilla to reach the base of the 

 axile corpuscle, as a fine, convoluted nervous twig of 0-006--012 of a line 

 in thickness. Here the nerve frequently becomes invisible, so that, as has 

 happened to Wagner, one may be led to believe that it enters the cor- 

 puscle, which is seated upon it, as upon a stalk, and there ends. How- 

 ever, if a number of fresh preparations be treated with acetic acid and 

 examined, the conviction is soon arrived at that this is merely apparent, 

 the nervous tubules in reality proceeding aloyig the outer surface of the 

 corpuscle, either as far as its point, or very nearly so. In the mean- 

 Avhile they either remain together or take an isolated course. In both 

 cases their neurilemma becomes excessively delicate, appearing finally 

 to vanish entirely, while the nerves themselves surround the axile cor- 

 puscle, passing round it either more directly, though in a slightly undu- 

 lating course, or forming one or several spiral coils (Fig. 54, B). As 

 regards the actual termination of the nervous tubules, I retain the opi- 

 nion I formerly expressed, inasmuch as, in at least six cases, I have 

 again most distinctly seen loops (Fig. 54). It is, however, always difficult 

 to observe them, and very frequently impossible, in spite of every exer- 

 tion; and therefore, as we are all liable to error, I will blame no one for 

 considering the termination of the nerves of the papillse to be unknown, 

 or for believing in the existence of free ends, which perhaps also exist, 

 and, at any rate, very frequently appear to exist. I only state what, 

 according to my best belief, I have seen ; and while I have no prejudice 

 in favor of loops, neither can I see anything alarming in their existence. 

 This much, however, is certain, that Wagner has not traced the nerves 

 in the papillae so far as they may be traced, and therefore, at present 

 at all events, can lay no claim to a decisive voice in the matter. How 

 the nerves in the papillae of the lips, tongue, and elsewhere, are disposed, 

 I have not yet ascertained with certainty ; but with regard to the first 

 of these, I believe I can also afiirra, that they do not terminate in the 

 axile corpuscles, but either merely pass by them or wind round them. 

 In the lips, in a single instance, I found well-marked nerve-coils in small 

 papill?e, or at the base of the large ones. 



§ 38. Development of the Cutis. — The following may be taken as a 



* [It is by no means easy to recognize this neurilemma. Indeed, even its existence is ques- 

 tioned by Meissner, who states that after the most careful observation, he has not been able to 

 detect a neurilemma in one single instance. The nerve itself he thinks does not terminate in 

 loops, as stipposed by Kolliker, but penetrates into the tactile corpuscles. The cross-striae 

 considered by Kolliker as elastic tissue, he justly describes as the termination of the dark- 

 bordered nerve-tubules, for the action of soda on them proves them to be such. — DaC] 



