Chap. XXVII. PKOVISIONAL HYPOTHESIS OF PANGENESIS. 357 



CHAPTER XXVII. 



PROVISIONAL HYPOTHESIS OF PANGENESIS. 



PRELIMINARY REMARKS. — FIRST PART I — THE FACTS TO BE CONNECTED UNDER A 

 SINGLE POINT OF VIEW, NAMELY, THE VARIOUS KINDS OF REPRODUCTION — THE 

 DIRECT ACTION OF THE MALE ELEMENT ON THE FEMALE — DEVELOPMENT — 

 THE FUNCTIONAL INDEPENDENCE OF THE ELEMENTS OR UNITS OF THE BODY — 

 VARIABILITY — INHERITANCE — REVERSION. 



SECOND PART : — STATEMENT OF THE HYPOTHESIS —HOW FAR THE NECESSARY ASSUMP- 

 TIONS ARE IMPROBABLE — EXPLANATION BY AID OF THE HYPOTHESIS OF THE 

 SEVERAL CLASSES OF FACTS SPECIFIED IN THE FIRST PART — CONCLUSION. 



In the previous chapters large classes of facts, such as those bear- 

 ing on bud- variation, the various forms of inheritance, the causes 

 and laws of variation, have been discussed ; and it is obvious that 

 these subjects, as well as the several modes of reproduction, 

 stand in some sort of relation to each other. I have been led, 

 or rather forced, to form a view which to a certain extent 

 connects these facts by a tangible method. Every one would 

 wish to explain to himself, even in an imperfect manner, how it 

 is possible for a character possessed by some remote ancestor 

 suddenly to reappear in the offspring; how the effects of 

 increased or decreased use of a limb can be transmitted to the 

 child; how the male sexual element can act not solely on 

 the ovule, but occasionally on the mother-form ; how a limb can 

 be reproduced on the exact line of amputation, with neither too 

 much nor too little added; how it comes that organic beings 

 identical in every respect are habitually produced by such 

 widely different processes, as budding and true seminal genera- 

 tion. I am aware that my view is merely a provisional hypo- 

 thesis or speculation; but until a better one be advanced, it 

 may be serviceable by bringing together a multitude of facts 

 which are at present left disconnected by any efficient cause. 

 As Whewell, the historian of the inductive sciences, remarks :— 

 "Hypotheses may often be of service to science, when they 

 "involve a certain portion of incompleteness, and even of error." 

 Under this point of view I venture to advance the hypothesis of 



