In a matter of scientific inquiry one cannot go far wrong if one follows the advice of Henri Poincaré, who lays down certain principles of method; four of these are the following:—

(1) The most interesting facts are those which can be used several times, those which have a chance of recurring.

(2) The facts which have a chance of recurring are simple facts.

(3) Method is the selection of facts, and accordingly our first care must be to devise a method.

(4) We should look for the cases in which the rule established stands the best chance of being found fault with.

The groups of facts described in the succeeding chapters are in agreement with these principles in the main, and are perhaps like a dust heap for their intrinsic value. But one knows that before now among a good deal of débris a rusty key has been found which has opened a cabinet containing certain treasures, and in the hands of someone else than the finder has produced useful results.

The headings of the chapters describe the facts, and there is no need to enumerate them here. The first and largest group is studied according to a method which is in a measure applied to all the others. Most of them are external or superficial phenomena and accordingly are open to others beside the expert for observa-tion and corrobora-tion, or the reverse. The typical plan adopted is as follows: a large number of related phenomena are chosen, and the more prominent of these are observed and described. Keeping in mind the two plain issues laid down, the origin of initial modifications and their transmission, I have selected the facts because, especially such as those of the hair, they are very simple, of wide distribu-tion in animals well known to us, such as the domestic horse and man, and none are brought forward which any other observer cannot study for himself if he has some anatomical and physiological knowledge, some training and care in recording observations. In most centres of popula-tion there are still left a good supply of horses in streets and stables, of preserved specimens in museums and living ones in zoological gardens, and of hairy young men who
will hardly refuse a polite request to examine the minute hairs clothing their trunks and limbs. One has to pursue a certain amount of that study which may be called the sister of plant-ecology, that is, animal-ecology or the behaviour of animals at home. The student of these matters, it may be freely admitted, will complain, unless he has some hypothesis or line of thought to follow, that he has been set down in a valley in which the bones are very many and very dry. But, armed or primed with an hypothesis, he may find an affirmative answer to his question “Can these bones live?” Every group of natural phenomena, without exception, has some meaning for those who will interpret nature rather than bully and slight her, and whatever anointed king may claim sovereignty over it the humble fact cannot be denied that “whatever phenomenon is, is.”40 Again I would refer to Howes’ inspiring note: “We live by ideas; we advance by a knowledge of the facts; content to discover the meaning of phenomena, since the nature of things will be for ever beyond our grasp.”41 The facts adduced are simple, have a chance of recurring and are widely distributed among multicellular animals—the botanists and plants can very well take care of themselves. I must once more state that I am attaching to the considered facts a value of a somewhat unusual kind—their intrinsic unimportance. For anyone who has had to encounter the skilful dialectics and counter-attacks of a well-equipped neo-Darwinian it is well that he should remember the maxim of Napoleon, “Be vulnerable nowhere.” It is necessary to show evidence for Lamarckian factors in which no degree of selective value, survival-value, can be seen by hostile sharp-shooter while he works in his trench. The main line of defence, or more correctly what Hindenburg would call “offensive-defence,” is therefore made to rest on the phenomena of hair-direction, which, I submit, are impregnable to the forces of selection, probably in all the hairy mammals, but certainly in that hairy animal called Man.
Thesis.

If these groups of phenomena were being studied apart from the hypothesis they support, a much more full treatment of all of them would be required, such as I have given to those of hair-direction in a book published in 1903 on Direction of Hair in Animals and Man. The limited thesis, however, here upheld is that the phenomena are produced by the factors of stimuli and response in
the course of the total experience of the organism, that the essence of the matter is the produc-tion of initial modifications, that instances of these in well-known animals are produced before our eyes by ascertainable mechanical stimuli, and that, especially in those of hair-direction, experiment is adduced in proof of the thesis that some modifications are transmitted.
Procedure.

The order of proceedings may be tabulated thus:—

(1) Observation of selected facts.

(2) Evidence that certain of these are produced in the lifetime of the individual.

(3) Evidence that among the facts of direction of hair and others there is to be seen an orderly evolution rather than a casual appearance of the changes noted.

(4) An hypothesis as to their production.

(5) Exclusion of selection as a possible cause of these, and of correla-tion as properly understood.

(6) Experiment in verification of the Lamarckian interpreta-tion of the phenomena.

And here, before I hear some Prince Henry of the genus Weismann, Mendel or Gallio groan aloud: “This intolerable amount of sack,” I proceed to offer him a few loaves of home-made bread.