264 
IOWA ACADEMY OF SCIENCES 
under 50 to 100 diameters and the ones best showing nerve structures 
sorted out. These latter mounted in glycerine on slides will flatten out 
under slight pressure upon the cover glass so as to enable one to con- 
tinue the examination with higher power of the microscope. These 
structures are quite delicate and when once mounted cannot be further 
manipulated for difCerent views. For this reason there is an advantage 
in mounting material between large cover glasses in as much as both 
sides of the preparation may then be viewed. There is this disadvantage, 
however, that such a preparation cannot be preserved long. 
In addition to the above process stained tissue w'-as hardened in alco- 
hol, embedded in paraffln, sectioned and examined in series. Varions* 
counter stains were employed but with very little success thus far. 
As to my own results I am convinced that the primary nerve fibre 
neither terminates in an end or ground plate, or granular sole, nor pierces 
the sarcolemma, at least at that point. It would seem to me that the 
sole nuclei described by Huber-Dewitt and others were end bulbs belong- 
ing to the ultimate branches of the axis-cylinder. For by this method 
unless a particular preparation is stained quite perfectly only a few of 
the end fibrils can be traced, while their granular nuclear-appearing 
bunches or knobs appear quite conspicuous, but disconnected. I was for 
some time of the opinion myself that these apparently isolated knobs 
belonged to the muscle fibre, and that the muscle fibre was consequently 
specialized at these places for receiving the nerve endings. But by 
observing that the best stained preparations showed all of these knobs 
or bulbs to be either connected, or partly so, by fine nerve fibrils, I con- 
cluded that such would be the case with all of them if the staining was 
sufficiently perfect. Later observations confirm the belief. There seems 
to be no regular order, size, shape or number of either the end fibrils or 
end bulbs. Generally the fibrils are relatively short and the bulbs are 
elongated and more pointed at the distal ends. Plexuses among the 
fibrils are occasionally found. The fibrils show by their pale outline 
down to their tips a covering of connective tissue which is probably a 
continuation *of the neurilemma. In my observation no neurilemma 
nuclei have been seen upon them, but this does not argue much for the 
absence of neurilemma here, in as much as neurilemma nuclei of the 
main fibre are generally much farther apart than the entire length of 
these fibrils. These structures seem to be connected more or less with 
the sarcolemma, as may be seen by their adhesion to that membrane 
when being torn off. The relation seems to be either that of intermuscu- 
lar connective tissue joining fibrils and bulbs to the sarcolemma, or a 
superficial coalescence between nburilemma and sarcolemma. In the 
examination of a very great number of cross and longitudinal sections 
no point could be found where either bulbs or fibrils were beneath the 
sarcolemma. In the fibrils the medullary sheath is either present in very 
slight amount or is entirely wanting. Figure 1 is fairly typical of this 
structure. Exceptional forms are occasionally found differing widely 
from the typical. 
