Mabch 12, 1909] 



SCIENCE 



435 



Color Inheritance in Crosses Between the Black 

 Rat (Mus rattus) and the Boof Bat (Mus alex- 

 andrinus) : T. H. Mobgan, Columbia University. 

 (See American 'Naturalist, 1909.) 

 Some Methods and Besults of Pigeon Breeding at 

 the Rhode Island Eccperiment Station,: L. J. 

 CoEE, Yale University. 

 Preliminary Statistics on the Nidification and the 

 Proportions of the Sexes in Pigeons: L. J. C!oije, 

 Yale University. 

 The Inheritance of Egg-producing Ability (Fe- 

 cundity) in the Domestic Fowl: Raymond 

 Peabl and Fbank M. Stjeface, Maine Agricul- 

 tural Experiment Station. 



The data discussed in this paper were obtained 

 from two lines of work. The first of these was an 

 experiment in which for a period of nine years 

 hens have been selected for high egg production. 

 No hens were used as breeders whose production 

 in the pullet year had not been 150 or more eggs. 

 The cockerels used were, after the first year of 

 the experiment, invariably the sons of mothers 

 producing 200 or more eggs in their pullet year. 

 The second source of data was an experiment 

 in which the inheritance of egg production from 

 mother to daughter was directly measured. Eec- 

 ords of the pullet year egg production of 250 

 daughters of hens laying 200 or more eggs in 

 their (the mothers') pullet year were obtained. 

 Certain of the most important results obtained 

 may be summarily stated as follows: 



1. Selection for high egg production carried on 

 for nine consecutive years did not lead to any 

 increase in the average production of the flocks. 



2. There was no decrease in variability in egg 

 production as a result of this selection. 



3. The present data give no evidence that there 

 is a sensible correlation between mother and 

 daughter in respect to egg production, or that 

 egg-producing ability (fecundity) is sensibly in- 

 herited. 



4. In this experiment the daughters of "200- 

 egg" hens did not exhibit, when kept under the 

 same environmental conditions, such a high av- 

 erage egg production as did pullets of the same 

 age which were the daughters of birds whose pro- 

 duction was less than 200 eggs per year. 



5. The daughters of " 200-^g " hens were not 

 less variable in respect to egg production than 

 were similar birds whose mothers were not so 

 closely selected. 



Color Changes of Ocypoda arenaria: E. P. Cowiaa, 

 Johns Hopkins University. 



Under certain conditions a dark color pattern 

 can be distinctly seen through the carapace of 

 Ocypoda arenaria; under other conditions this 

 pattern disappears. 



Many experiments were performed to test the 

 effect of intensity of light, degree of temperature, 

 mechanical and chemical stimtili. It was foimd 

 that the first two factors determined the appear- 

 ance and the disappearance of the color pattern. 



In direct and diffuse sunlight when the tem- 

 perature is kept low the pattern is visible, but 

 when the temperature is high the pattern dis- 

 appears. 



In the absence of light at low medium and high 

 temperature the pattern fails to appear. 



Of the two factors, intensity of light and de- 

 gree of temperature, the former is the more im- 

 portant. 



A Chynandromorphous Crayfish: E. A, Andeews, 



Johns Hopkins University. 



A specimen of Camiaru^ affinis proves upon 

 study to be an immature male with a few external 

 sex organs that should appear only upon the 

 female. 



This gynandromorph, or individual with a mix- 

 ture of organs normally found upon two individ- 

 uals, male and female, has a normal testis with 

 no sign of ovogenesis, and two normal, but little 

 developed deferent ducts and the two normal male 

 papillae at the bases of the fifth thoracic legs. 

 Moreover, the limbs of the first and the second 

 abdominal somites are as in a normal young 

 male and the hooks of the third thoracic legs are 

 normal. 



On the other hand, the third thoracic legs bear 

 two elliptical openings that closely imitate the 

 openings of oviducts. These openings are mere 

 blind cuticular structures and do not communicate 

 with any internal organs. 



Most of the gynandromorph crayfishes hitherto 

 known have been females with some male traits. 



This case emphasizes the independence of gonad 

 and external sex organ, and is in opposition to 

 internal secretions as a cause of appearance of 

 external sex organs. 



Whether such mixtures of sex organs can be due 

 to abnormal fertilizations, to polyspermy, may 

 be decided by future experiments in cross breed- 

 ing of crayfish. At present the evidence seems to- 

 indicate that these gynandromorphs may arise in 

 the ovarian egg. 



Organs of Sperm-transfer in Male Crayfish: E. A.. 

 Andbews, Johns Hopkins University. 



