In 1868, thinking that an untechnical statement of the views current among the leaders of biological science might be interesting to the general public, I gave a lecture embodying them in Edinburgh.  Those who have not made the mistake of attempting to approach biology, either by the high a priori road of mere philosophical speculation, or by the mere low a posteriori lane offered by the tube of a microscope, but have taken the trouble to become acquainted with well-ascertained facts and with their history, will not need to be told that in what I had to say “as regards protoplasm” in my lecture “On the Physical Basis of Life” (Vol.  I. of these Essays, p. 130), there was nothing new; and, as I hope, nothing that the present state of knowledge does not justify us in believing to be true.  Under these circumstances, my surprise may be imagined, when I found, that the mere statement of facts and of views, long familiar to me as part of the common scientific property of Continental workers, raised a sort of storm in this country, not only by exciting the wrath of unscientific persons whose pet prejudices they seemed to touch, but by giving rise to quite superfluous explosions on the part of some who should have been better informed.

Dr. Stirling, for example, made my essay the subject of a special critical lecture,[9] which I have read with much interest, though, I confess, the meaning of much of it remains as dark to me as does the “Secret of Hegel” after Dr. Stirling’s elaborate revelation of it.  Dr. Stirling’s method of dealing with the subject is peculiar.  “Protoplasm” is a question of history, so far as it is a name; of fact, so far as it is a thing.  Dr. Stirling, has not taken the trouble to refer to the original authorities for his history, which is consequently a travesty; and still less has he concerned himself with looking at the facts, but contents himself with taking them also at second-hand.  A most amusing example of this fashion of dealing with scientific statements is furnished by Dr. Stirling’s remarks upon my account of the protoplasm of the nettle hair.  That account was drawn up from careful and often-repeated observation of the facts.  Dr. Stirling thinks he is offering a valid criticism, when he says that my valued friend Professor Stricker gives a somewhat different statement about protoplasm.  But why in the world did not this distinguished Hegelian look at a nettle hair for himself, before venturing to speak about the matter at all?  Why trouble himself about what either Stricker or I say, when any tyro can see the facts for himself, if he is provided with those not rare articles, a nettle and a microscope?  But I suppose this would have been “Aufklaerung”—­a recurrence to the base common-sense philosophy of the eighteenth century, which liked to see before it believed, and to understand before it criticised Dr. Stirling winds up his paper with the following paragraph:—­

[Footnote 9:  Subsequently published under the title of “As regards Protoplasm.”]