20 ON THE MINUTE STRUCTURE OF 
being produced by the whole material of the long muscular elements being 
drawn together into so small a compass. The rounded appearance of the nuclei 
was accounted for by supposing either that they had themselves contracted, 
or that they had been pinched up by the contracting fibres, of which explana- 
tions the latter appears the more probable. 
In order to place the matter if possible beyond doubt, I prepared two 
contiguous portions of the circular coat of a contracted piece of intestine in 
different ways; the one by simply cutting off a minute portion with sharp 
scissors, so as to avoid as much as possible any stretching of the tissue, the 
other by purposely drawing out a fasciculus to a very considerable length, 
and then teasing it with needles. In the former preparation, the fibre-cells 
appeared all of them more or less contracted, except in parts where the slight 
traction inseparable from any mode of preparation had stretched the pliant 
tissue, which in the fresh state appears to yield as readily to any extending 
force as does a relaxed muscle of a living limb. In the other object, where the 
tissue had been purposely stretched, most of the fibre-cells were extended, 
and possessed elongated nuclei. Here and there one would be seen of excessive 
tenuity, scarcely broader at its thickest part than the nucleus, looking, under 
the highest magnifying power, like a delicate thread of spun glass. To how 
great a length the fibre-cells admit of being drawn out in this way without 
breaking I cannot tell. Fig. 1 represents a portion of such a fibre with the 
contained nucleus. Among these extended fibres, however, there lay, here 
and there, an extremely contracted one, the result, I have no doubt, of the 
irritation produced by the needles upon the yet living tissue. In order to guard 
against this source of fallacy, I kept a piece of contracted gut forty-eight hours, 
and then examined two contiguous parts of the circular coat in the way above 
described. The muscle was much less readily extended than in the fresh state, 
and I found that, where stretching of the tissue had been avoided as much 
as possible, it was composed entirely of fibre-cells marked with transverse 
ridges of varying thickness and proximity ; a minute fibril having, under 
arather low power, the general aspect represented in Fig. 17. But I saw no 
distinct examples of the extreme degree of contraction so frequent in muscle 
from the same piece of intestine in the fresh state. This confirmed my sus- 
picion that the latter had been induced by the irritation of the mode of pre- 
paration. On the other hand, a fully stretched fasciculus showed its fibres 
everywhere destitute of transverse rugae, so that the point was now distinctly 
proved. Kolliker, in his original article in the Zeitschrift fir wissenschaftliche 
Zoologie, figured some long fibre-cells with transverse lines upon them,‘ knotty 
swellings ’, as he termed them, which he supposed probably due to contraction, 
