July 28, 1911] 



SCIENCE 



115 



misstates certain facts which I can not pass 

 over in silence, lest this be interpreted 

 as assent. He states, first, that we used 

 " mongrel stock." " Therefore, any evidence 

 furnished by the character of the offspring 

 would be of doubtful value." On what 

 Guthrie bases this statement I am unable 

 to discover. It is wholly contrary to fact. 

 "We described in the body of our paper " one 

 successful case " and in a postscript a 

 second case complete except as regards the 

 autopsy. In describing the successful case, 

 p. 8, the statement is expressly made that the 

 ovary was taken from " a pure black guinea- 

 pig." This guinea-pig belonged to a family 

 of coal-black animals which I have had for 

 about seven years. This family is descended 

 without admixture of other blood from three 

 original individuals, a male and two females, 

 all intensely black, the progeny of which have 

 been closely inbred now for several genera- 

 tions without ever producing any observable 

 deviation from the solid black type of the 

 progenitors. The albino grafted was also of 

 pure race, one which I have bred for about 

 ten years. The albino male with which the 

 grafted animal was mated was of a different 

 strain, but of known and tested gametic com- 

 position, so that I can state with much posi- 

 tiveness the kind of young which he produced 

 (and would regularly produce) in matings 

 with guinea-pigs of different color varieties. 

 The second successful case, described in a 

 postscript, concerned a color variety which I 

 originated, the brown-eyed cream, and which 

 breeds very true, since all the color factors 

 which it contains save one are recessive in 

 nature. This variety can produce only one 

 variety of colored young. It is the ulti- 

 mate recessive colored variety of guinea-pig. 

 Having originated this variety some years ago 

 and bred it pure and in crosses ever since, I 

 think I may justly claim to know something 

 about its behavior in inheritance. In neither 

 of the cases which we have described as " suc- 

 cessful " was an animal used whose breeding 

 capacity was not definitely and fully known, 

 as definitely as we know what will happen 

 when oxygen and hydrogen are combined. 



The charge of " mongrel stock " is therefore 

 groundless. 



Guthrie's second criticism of our evidence is 

 this, " It is not proved that the offspring may 

 not have come from ovarian tissue of the host 

 left in site after operation." But both the 

 grafted animals were albinos and they were 

 mated only with albino males. In all recorded 

 cases, of which I have myself observed many 

 hundred, albinos so mated produce only albino 

 young. Had ovarian tissue been left in site 

 after operation and liberated ova which devel- 

 oped, these should have produced albino 

 young. But these grafted albinos, which had 

 received an ovary from a colored animal, pro- 

 duced colored young, in each case of the par- 

 ticular color type that characterized the ani- 

 mal furnishing the graft. Is there really 

 then any uncertainty about the source from 

 which the functioning ova came? 



W. E. Castle 



Laboratory op Genetics, 

 BussEY Institution, 

 Harvard University, 

 June 21, 1911 



measuring the merit of ENGLISH WRITING 



To THE Editor op Science: Professor 

 Thorndike's article in Science of June 18 on 

 a scale for measuring the merit of English 

 writing, seems to parallel the old question: 

 " Which is best, a pair of scissors or a pair 

 of tongs ? " 



To have any value as a test of merit the 

 writing of " pupils in their teens " should be 

 comparative, and you can not properly com- 

 pare paragraphs based on different topics, 

 recollections or quotations from school read- 

 ers, and attempts at expression of totally dis- 

 tinct emotions. 



One method which might approximate to a 

 basis of comparison would be to require from 

 all the pupils a paraphrase of one single para- 

 graph, as far as possible to be expressed in 

 entirely different words from the original. 

 Even this would be subject to the objection 

 that a child writes best when it writes of 

 something it naturally appreciates, and in 

 which its interest is not forced; and the same 



