300 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Otolith-method of Estimating Age of Plaice.— H. Chas. William- 

 son {Journ. Zool. Research, 1918, 3, 13-29, 17 figs.) criticizes Reibisch's 

 otolith-method of estimating the age of the plaice, which was based on 

 the postulate that the rings seen in the structure of the otolith are 

 year-rings. It is maintained that this postulate does not rest on any- 

 solid basis, and that the assumption that all plaice three years old are 

 mature is at variance with the facts. J. A. T. 



Rings in Scales of Plaice and Flounders. — D. Ward Cutler 

 {Journ. Marine Biol. Assoc, 1918, 11, -1:70-96) has made experiments 

 on scale growth, and concludes that the broad summer bands, produced 

 by broad sclerites, and the narrow winter bands, produced by narrow 

 sclerites, are due to changes in the temperature of the w^ater. As 

 the temperature varies from month to month, or even from week 

 to week, the scale curves do not show a continuous rise and fall, but 

 exhibit at certain places secondary elevations or depressions, secondary 

 maxima and minima. The amount of food does not affect the produc- 

 tion of summer and winter bands, save that poor nutrition tends to 

 there being few sclerites produced, and high food consumption leads to 

 high sclerite formation. Cutler's view is against that of J. Stuart 

 Thomson, who concluded that the amount of food supply, rather than 

 variation in temperature, brought about the formation of annual rings 

 in scales. J. A. T. 



Blue Andalusians. — W. A. Lippincott {Ayner. Naturalist, 1918, 

 52, 95-115) finds that blue Andalusians are like black Andalusians 

 in that they are self-coloured. They are like the blue-splashed in that 

 homologous pigmented feathers in both sexes have the same condition 

 with reference to the restriction of pigment in the feather structure. 

 The fundamental phenotypic differences between black, blue and l)lue- 

 splashed Andalusians are briefly described. It is pointed out that the 

 1:2:1 ratio is in reality a combination of two 3 : 1 ratios. The con- 

 dition in the blues is shown to be due to the combined action of two 

 factors R and E. R acts on black pigment, restricting its distribution 

 in such a way that it gives the characteristic blue-grey appearance, 

 E extends black pigment to every feather on the fowl's body. It is 

 impossible to decide on the basis of present facts whether R and E are 

 located on identical loci of homologous chromosomes or are the domi- 

 nants of two pairs of factors, each linked to the recessive allelomorph of 

 the other. J. A. T. 



Baculum or Os penis in some Genera of Mustelidse. — R. I. Pocock 

 {Ann. Nat. Hist., 1918, 1, series 9, 307-12, 12 figs.) confirms in regard 

 to some Mustelidte what Oldfield Thomas has shown for Sciuridas, that 

 the baculum has great systematic value as an index of affinities. He 

 deals with the genera Gharronia, Grison, and Mellivora, and attention is 

 drawn to the singular differences between the bacula of llustela erminea 

 and M. nivalis. By the shape of the bone the latter falls into the same 

 category as Mustela {Putorius) putorius and faro. In 31. africana the 

 bone is shaped substantially as in M. nivalis. J. A. T. 



