628 APPENDIX B. 



" recollection is mucli less perfect than I wish it to be." He also 

 adds that, in the course of many years' experience, he had never 

 known the least appearance of the chestnut colour in Mr. West- 

 ern's breed. 



What are the probabilities that these two anomalous results 

 should have arisen, under these exceptional conditions, as a 

 matter of chance ? Evidently the probabilities against such a 

 coincidence are enormous. The testimony is in both cases so 

 good that, even apart from the coincidence, it would be unreason- 

 able to reject it ; but the coincidence makes acceptance of it im- 

 perative. There is mutual verification, at the same time that 

 there is a joint interpretation yielded of the strange phenomenon, 

 and of its non-occurrence under ordinary circumstances. 



And now, in presence of these facts, what are we to say ? 

 Simply that they are fatal to Weismann's hypothesis. They show 

 that there is none of the alleged independence of the reproductive 

 cells ; but that the two sets of cells are in close communion. 

 They prove that while the reproductive cells multiply and arrange 

 themselves during the evolution of the embryo, some of their 

 germ-plasm passes into the mass of somatic cells constituting the 

 parental body, and becomes a permanent component of it. Fur- 

 ther, they necessitate the inference that this introduced germ- 

 plasm, everywhere diffused, is some of it included in the repro- 

 ductive cells subsequently formed. And if we thus get a demon- 

 stration that the somewhat different units of a foreign germ-plasm 

 permeating the organism, permeate also the subsequently formed 

 reproductive cells, and affect the structures of the individuals 

 arising from them, the implication is that the like happens with 

 those native units which have been made somewhat different by 

 modified functions : there must be a tendency to inheritance of 

 acquired characters. 



One more step only has to be taken. It remains to ask what 

 is the flaw in the assumption with which Weismann's theory sets 

 out. If, as we see, the conclusions drawn from it do not corre- 

 spond to the facts, then, either the reasoning is invalid, or the 

 original postulate is untrue. Leaving aside all questions con- 

 cerning the reasoning, it will suffice here to show the untruth of 

 the postulate. Had his work been written during the early 

 years of the cell- doctrine, the supposition that the multiplying 

 cells of which the Metazoa and Metaphyta are composed, become 

 completely separate, could not have been met by a reason- 

 able scepticism ; but now, not only is scepticism justifiable, but 

 denial is called for. Some dozen years ago it was discovered thr.t 

 in many cases vegetal cells are connected with one another by 

 threads of protoplasm — threads which unite the internal proto- 

 plasm of one cell with the internal protoplasms of cells around 



