CAUSE OF STRIATION OF VOLUNTARY MUSCULAR TISSUE, 325 
the darker. If good specimens of insects’ muscle be examined, 
which have been treated with osmic acid, and if the fibre be not 
sheared, the valley is always bright in the ordinary or deeper 
focus. I have verified this point in very many cases. Passing 
along a fibre from the relaxed end to a part where the contraction 
is fullest, the appearances vary in degree, but not in kind. The 
main features are in both cases the same, but the stripes are 
now narrower, and often it is not so easy to see Dobie’s and 
Hensen’s stripes. It follows, from the statement of Engelmann’s, 
“the bright stripes become darker than the dim,” as he himself 
notices that at one point, or phase, in the contraction, no striping 
is to be made out. We agree with Ranvier that this is not 
true ; indeed, it would be impossible for a muscular fibre with 
its configuration not to be marked across its length. 
This subject will call up to the mind of every working his- 
tologist appearances which he must have met with in other fields 
of research. Many tissues naturally, or after clumsy manipula- 
tion, present ampullations which always coexist with cross striz. 
The fibres of the crystalline lens are wavy in outline, and when 
many of them are bound together and seen on edge with the 
wavy outline towards the eye of the observer, cross bands are 
seen which in chance preparations (especially those of the frog’s 
lens) simulate muscle in a wonderful manner. Ordinary non- 
striped muscle, which may be so well seen in the frog’s bladder, 
is often faintly ampullated, especially, perhaps, in chloride-of- 
gold preparations. Cross stripes may also here be seen. The 
fibres of Tomes, when a section of softened tooth is teazed, are 
pulled out of the dentinal tubules, and, being of a soft and some- 
what elastic nature, on breaking they become often very beauti- 
fully ampullated, and it would be impossible to distinguish them 
from muscular fibrille. In the class of practical histology, on 
more than one occasion students have asked me the meaning 
of beautiful cross shadings seen on nerve fibres; a slight 
ampullation, which fully accounted for it, was always found. 
Many more instances of a like nature will be recalled in the 
experience of every one; it is needless to enumerate further. 
In the winter of 1879-80, while examining fibres of the 
muscles of a newly-born child, a very curious: discovery was 
made. A nucleus adhering to the sarcolemma was seen beau- 
tifully striped. It was not in close apposition to the fibre, a very 
narrow chink intervening. On focussing with great care, it 
was seen that the cross bands upon it corresponded with those 
of the adjoining fibre, a dark one, however, for a light one, and 
vice versa (fig. 6). Now, the curious point was that the nucleus 
had evidently been impressed by the fibre, moulded upon it, 
as it were, and on being pulled apart had presented a perfect 
