D. J. SCOURFIELD ON MENDELI8M AND MICROSCOPY. 419 



The foregoing views as to the hearing of Mendelism on 

 fundamental biological problems naturally depend for their 

 justification very largely upon the extent to which Mendel's 

 law applies. This, however, is still an unsolved problem. For 

 many characters in many plants and animals, including man, 

 the law seems to be demonstrably true, but as regards a 

 much larger number of characters it is not known at present 

 whether they follow it or not, and it is the task of present- 

 day investigators to throw light on this matter. But, quite 

 apart from whether his law be ultimately proved to be very 

 limited in its sphere of influence, or whether it be found to 

 be of universal application, we still owe a very great deal to 

 the work of Mendel. He has given to horticulturists and breeder^ 

 a working hypothesis which will certainly prove of the greatest 

 value in the rapid production and fixing of new varieties. For 

 example, Hurst has shown incidentally, in the course of his 

 experiments carried out in accordance with Mendelian principles, 

 that eight of the named fancy breeds of rabbits can be obtained 

 from a cross between a "Belgian hare" and a '"white Angora," 

 so that if by accident these races were entirely lost they could 

 be replaced at any time without difficulty. "When the uncertainty 

 involved in producing pure races by the usual methods is remem- 

 bered, this result is certainly a triumph. To biologists Mendel 

 has opened up a new field of experimental work the importance 

 of which it is very difficult to overestimate. He has shown, in 

 fact, how the thin end of the wedge may be inserted into what 

 has hitherto been one of the most refractory of biological problems. 

 Finally, to all scientific workers, but especially to those who 

 pursue scientific studies rather as a recreation than a profession, 

 Mendel has set a fine example of patient investigation carried out 

 with perfectly simple material.-. 



Bibliography. 



Bailey, L. H. Plant-breeding, 4th edition, 1906, pp. 143—226. 



Bateson, W. MendeVs Principles of Heredity, 1902.— "Presidential 

 Address," Section D (Zoology), British Association, Cam- 

 bridge, 1904 (printed in Xature, August 25th, 1904, pp. 



406 413). — "Mendelian Heredity and its Application to 



Man." Brit. Medical Journal, July 14th, 1906, pp. 61—67. 



