April, 1914 



THE GARDEN AND FIELD. 



First, as to the fact :— The 

 lowiujj are simple statements of 

 the actual results obtained in Irap- 

 nestin^ Barred I'lyiuouth Rocks 

 mvd Cornish Indian Ganii'S, and 

 all possible sorts of crosses be- 

 tween these breixls, over a period 

 collecti\ely of nearly fifteen years. 

 Tire total number of birds involved 

 in these trap-nesting operations 

 has been lari;;v, a_<,'-iireg'ating all told 

 between 5,000 and 6,000 indivi- 

 duals. Out of these records, the 

 following facts clearly appear i — 



1. The record of egg production 

 of a hen, taken by itself alone, 

 gives no definite reliable indica- 

 tion from which the probable egg 

 production of her daughters may 

 be predicted. Furthermore, mass 

 selection on the basis of egg-laying 

 records of females alone, even 

 thotigh long continued and string- 

 ent in character, failed completely 

 to produce any steady change in 

 type in the direction of selection. 



2. Differences in egg producing 

 ability are, in spite of the above 

 results, certainly inherited. There 

 are two lines of evidence showing 

 that this is the case. The first 

 is that derived from the general 

 observation that there are widely 

 distinct and permanent (under or- 

 dinary breeding) differences in re- 

 spect to egg laying ability between 

 different breeds ol fowls and be- 

 tween different strains within the 

 same breed. In the second place, 

 a stud}' of pedigree records of 

 poultry at once discovers pedigree 

 lines in each of which a definite, 

 particular degree of egg producing 

 ability constantly re-appears, gene- 

 ration after generation, the "u 

 thus " breediiig true ' in this par- 

 ticular. With all birds kept under 

 the same general environmental 

 conditions, such a result can only 

 mean that the character is in some 

 manner inherited. 



3. The number of visible oocytes 

 on the ovary bears no definite or 

 constant relation to the actually 

 realised egg production. 



4. This can, only mean that ob- 

 served differences (variations) in 

 actual egg production uepend upon 

 differences in the complex physiolo- 

 gical mechanism concerned with th^ 

 uevelopment of oocytes, and the 

 separation of them from the ovary 

 and the body (laying). 



For reasons which cannot be 

 gone into here on account of lack 

 of time, attention has been focused 

 during the later phases of my 

 study on winter egg production. 



5. It is found to be the case 

 that birds fall into three well-de- 



fined classes in respect to winter 

 egg production. These include (a) 

 birds of high winter records ; (b) 

 birds with low winter records ; and 

 (c) birds which do not lay at all 

 in the winter period. The divi- 

 sion point between (a) and (b) for 

 the Barred Plymouth Rocks used 

 in these experiments fall at a pro- 

 duction of about 30 eggs. 



The next step is to enquire for 

 each of these classes separately 

 how egg producing ability is in- 

 herited within she class. We may 

 first deal with high production. 



— Inherited from thei iSir«. — 



6. High productiveness may be 

 inherited by daughters from theix 

 sire indepeudent of the dam. 



This is proved by a mass of de- 

 tailed concrete evidenre presented 

 in the complete paper. This evi- 

 dence consists of the results of 

 mating after mating, in which the 

 same proportions of daughters 

 liigh laying abiUty are produced 

 by the same sire, whether he is 

 mated with dams which are poor 

 layers or with dams which are 

 high layers. 



7. High laying ability is not di- 

 rectly inherited by daughters from 

 their dam. 



This is proved by a number of 

 evidence ofi which the most import- 

 ant are : (a) that continued selec- 

 tion of high producing dams does 

 not alone alter in any way the 

 mean egg production of the daugh- 

 ters. If an alteration does ap- 

 pear in any case following such se- 

 lections, "lurther analysis shows 

 that some additional element other 

 than the dam's egg record came 

 into account in making the selec- 

 tions of breeders, (b) The propor- 

 tion of high producing daughters is 

 the same whether the dam is of 

 high or of low fecundity, provided 

 both are mated to the same male, 

 (c) The daughters of a high pro- 

 ducing dam' may be either Mgh lay- 

 ers or poor layers, depending on 

 their sire, (d) The proportion of 

 daughters which are medium or 

 poor layers is the same whether 

 the dam is a high or a poor pro- 

 ducer, provided both are mated to 

 the same male. 



8. Mediocre or poor laying abili- 

 ty may be inherited by the daugh- 

 ters from either sire, or dam, or 

 both. 



Now, all of these eight points 

 are merely statements of fact. 

 They are the results which any in- 

 telligent person who examined our 

 extensive trap-nest and pedigree 



records would be bound to reacli. 

 They depend in no way upon any 

 " theory " of inheritance. 1 can 

 assure those to whom IMendalisni 

 is as the proverbial red rag to tuc 

 bull, that nothing which has been 

 said so far is even to the slightest 

 degree tainted with this dreadful 

 (?) doctrine. 



An isolated fact does not . alone 

 contribute to the body of organ- 

 ized knowledge known as science. 

 Its relation to other facts must 

 first be understood. Now the facts 

 regarding egg production, which 

 have been set forth above, do, as 

 a matter of fact, accord in a re- 

 markable, clear manner with a 

 MendeUan interpretation of the in- 

 heritance of fecundity in the fowl. 

 Such an interpretation has been 

 worked out in detail in Bulletin 

 205. Through this interpreation 

 this isolated group of facts is 

 brouo-ht into relation with a much 

 wider range of facts about inheri- 

 tance in poultry and other ani- 

 mals. In this way we are much 

 better able to understand (in the 

 light of present knowledge) the 

 meaning of pur facts and on this 

 basis to make plans for investiga- 

 tions which shall take us again a 

 little further into the realm of the 

 unknown beyond the boundaries of 

 our present knowledge. 



(To be Continued) [ 



I absolutely -refuse to take second 

 place with any remedy (no matter 

 what price) for healing Bums, 

 Boils, Soncs, Cuts, etc., or Bron- 

 chitis in Children. 



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For further particulars apply — 



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'Phone 273. 



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