238 Royal Society :— 
disposed in linear succession, with their longer axes in the direction 
of the fibre, and never occur in irregular groups, as is sometimes the 
case both in birds and mammals, in which, consequently, the same 
kind of fibres are often broader at first. Thus formed, they lie side 
by side in bundles of different sizes, to which new fibres or new 
fibrillee are being continually added by a renewed process of develop- 
ment. Every fibre is the rudiment of several fibrille. At this 
period each lateral band constitutes a single fibrilla, which is often 
resolved into sarcous elements of great distinctness and beauty, while 
new and similar fibrille are developed along its sides in the way 
already explained. The subsequent series of changes do not differ 
materially from those that occur in the inferior classes. 
It is evident that this description of the development of muscular 
fibre is entirely opposed to the cellular theory of Schwann ; while it 
agrees in some points with that of Lebert (Annales des Scien. Nat. 
1849-50), but more with that of Savory (Phil. Trans. 1855). Inno 
instance have I found that nucleated cells, properly so called, are 
concerned in the office of development; for the finely granular blas- 
tema attached to the nuclei, although it frequently assumes the shape 
of a fusiform cell, is not invested with acell-wall, in the proper sense 
of the word. Such an envelope, however, is sometimes simulated by 
the investing sarcous substance or fine lateral fibrilla when they are 
first laid down on the sides of the fusiform mass and meet each other 
at each extremity to form a single fibre or process. Indeed, according 
to my own observations, as already remarked, this is precisely the 
mode in which the organic muscular-fibre-cell is developed ; so that 
the striped muscular fibre, instead of being the product of nucleated 
cells, would appear to be itself, at first, an instance or mode of cell- 
formation, which finds its prototype in the organic muscular fibre- 
cell, and in which the cell-wal/ is substituted and represented by the 
investing sarcous substance. 
January 23, 1862.—Major-General Sabine, R.A., President, 
in the Chair. 
«« Additional Observations and Experiments on the Influence of 
Physical Agents in the Development of the Tadpole and the Frog.” 
By John Higginbottom, Esq., F.R.S. 
In a former paper ‘On the Influence of Physical Agents on the 
development of the Tadpole of the Triton and the Frog,” which the 
Royal Society honoured with a place in the Philosophical Transac- 
tions for 1850, experiments were detailed to prove that the ovum of 
the frog (the Rana temporaria) underwent its metamorphosis in the 
absence of light, contrary to the experiments of Dr. W. F. Edwards 
of Paris, related in his work ‘On the Influence of Physical Agents 
on Life.’ 
My most satisfactory experiment was made in a rock cellar 30 
feet deep, where no solar light ever entered; the mean temperature 
of the cellar was 51° Fahr.,—I believe, the lowest temperature at 
which the transformation could be effected. 
The ova of the frog, just deposited, were placed in the cellar on 
