Miscellaneous. 145 
In my judgment, this is only another and more emphatic way of 
stating the coordination of structure and function which has been 
insisted on by Prof. Owen and other naturalists again and again. In 
the first passage that I have quoted all this dependence of structure 
on “conditions” is assumed to be true. In the second passage, 
assuming it to be true, it is generalized into a law. In the third 
passage, assuming the existence of the law, its results are assumed 
to be tolerably uniform. 3 
Now I am not aware that any number of assumptions, vague 
ideas, or guesses will make a discovery; and if they had done so, 
are we not entitled to assume that the discoverer, instead of pub- 
lishing it anonymously, in a few vague sentences at the end of a 
review in a specially professional periodical, would have avowed his 
great thought, and brought it prominently before naturalists who 
could judge of its value? especially as he is now anxious to have 
credit for it. 
I have also had an opportunity of referring to the ‘ Principles of 
Biology ;’ and although Mr. Spencer insists with admirable clearness 
on the correlation of structure and function, and, as in the review, 
on the modification of structures by “incident forces,” I did not 
notice that these ‘‘ incident forces’’ were defined; while, so far as I 
could understand, Mr. Spencer confessed that he did not altogether 
see how their results were produced. 
If this is a correct statement of Mr. Spencer’s vague hypothesis, 
I submit that, but for the terms “pressure and tension,’ and 
“mechanical theory,’’ our views have little in common. His appears 
to me to have been an idea evolved out of an intellectual conscious- 
ness of what ought to be. My view was arrived at inductively from 
a long investigation ; and it was only when I was assured by mathe- 
maticians, chemists, physicists, and others of their willingness to 
cooperate in eventually demonstrating the view, that I consented to 
publish a sketch of my method of studying the theory of the skele- 
ton. For it is a part of a larger system referring the phenomena of 
nature to their ultimate and actual physical causes, many of which 
in their applications to life are discussed in a book of mine shortly 
to be published, on ‘ The Dynamical Geology of Great Britain.” 
I am, Gentlemen, 
Very faithfully yours, 
Harry SEELEY. 
Note on the Phenomena of Muscular Contraction in the Vorticellee. 
By C. RoveGert. 
Living muscles can alternately shorten and elongate themselves : 
this is their characteristic property. In purely elastic organs short- 
ening only takes place after previous mechanical elongation ; the 
muscles, on the contrary, can shorten themselves without appearing 
to have undergone any extension. 
Whatever may be the causes of the elongation and shortening of 
the muscular fibres, whether these opposite states result from a 
Ann. & Mag. N. Hist. Ser. 3. Vol. xx. 10 
