SCIENTIFIC SUMMAEY. 
457 
once so complicated, and the theory so startling, that the mind at first 
naturally shrank from the reception of so bold a statement. Like every- 
thing, however, which came from the pen of a writer whom he had no 
hesitation, as far as his judgment went, in considering as by far the greatest 
observer of the age, whatever might be thought of bis theories when 
carried out to their extreme results, the subject demanded a careful and 
impartial consideration. Like the doctrine of natural selection, it was sure 
to modify more or less their modes of thought. Even supposing the theory 
unsound, it was to be observed, as Whewell remarked, as quoted by their 
author, ^Hypotheses may often be of service to science when they involve 
a certain portion of incompleteness and even of error.’ Mr. Darwin said 
himself that he had not made histology an especial branch of study, and he 
(Mr. Berkeley) had, therefore, less hesitation in expressing an individual 
opinion that he had laid too much stress on free cell formation, which was 
rather the exception than the rule.* Assuming the general truth of the 
theory that molecules endowed with certain attributes were cast off by the 
component cells, of such infinitesimal minuteness as to be capable of circu- 
lating with the fluids, and in the end to be present in the unimpregnated 
embryo cell and spermatozoid, capable either of lying dormant or inactive 
for a time, or when present in sufiicient potency of producing certain 
definite effects, it seemed far more probable that they should be capable, 
under favourable circumstances, of exercising an influence analogous to that 
which is exercised by the contents of the pollen tube or spermatozoid on 
the embryo sac than that these particles should be themselves developed 
into cells ; and imder some such modification the theory was far more likely 
to meet with anything like a general acceptation.” 
What is Natural Selection ? — It is to be hoped that the Mr. Harrison who 
was so funny on the subject of the Darwinian theory at the British Asso- 
ciation will take up some elementary work, and make himself familiar with 
the principles involved in the term Natural Selection. Anything more 
ridiculous than the following objection to Darwinianism we have not yet 
met with : — With regard to acorns dropping upon the ground, it often 
happened that the smallest ones sprang up while the largest ones died. It 
was external circumstance merely that decided the question, and it had 
nothing to do with ^ natural selection.’ ” Mr. Harrison is one of those who 
would say the moon is not the moon because it is a planet. 
The Lingual Membrane of Mollusea. — In a very interesting paper in the 
Quarterly Journal of Microscopical Science, Mr. Jabez Hogg, Sec. Ii.M.S., 
describes the peculiar dental structures of the tongues and palates of mol- 
lusks, and attempts to furnish a scheme for classification. Mr. Hogg’s 
paper is so essentially a paper of details that it would be impossible to abstract 
it here. The author’s observations have been made in part upon a very 
valuable collection (the Woodwardian) in the possession of Mr. F. G. Ed- 
wards. We are not so sanguine as Mr. Hogg in the belief that the study of 
the odontophore ” and mandible will one day reveal the origin of species 
* Mr. Darwin’s theory only assumes the formation of a cell from a mo- 
lecule. This is not free cell formation, and it is not the exception, but indeed 
the rule, in the development of animal tissues. — Ed. P.S.B. 
YOL. YII. — NO. XXIX. I I 
