ZOOLOGY AND BOTANY, MICROSCOPY', ETC. 457 



rhythmic contractility on the part of embryonic mesoderm cells under 

 cultural conditions, show that tlie life of cells in culture is not merely a 

 series of " survival phenomena " on a down-grade. 



Numerical Results of Diverse Systems of Breeding.*— H. S. Jennings 

 gives formula for finding in any generation the results of continued 

 breeding by a given system, with respect to a single pair of alternative 

 characters. Sex-linked characters and typical characters are dealt with 

 separately. Formula? are given for the results of random mating, 

 assortative mating, selection of dominants, self-fertilization and in- 

 breeding. In each case the diverse results obtained by beginning with 

 different parental combinations are given. It is shown that the results 

 in successive generations form fractions such as may be obtained by 

 compounding in various ways several well-known arithmetical series. 



Inheritance of Finger Peculiaritie s. — H. Drinkwater describes 

 peculiarities in fingers persistent for at least four generations. The 

 most striking peculiarity is a marked reduction in the length of the 

 index and middle fingers, so that the ring finger projects far beyond 

 the others. It is of the nature of brachydactyly, but there all the 

 fingers are affected. Both hands are similar. An interesting point is 

 the occurrence of an extra triangular bone interposed in the index and 

 middle fingers between the epiphysis of the proximal phalanx and the 

 head (epiphysis) of the metacarpal. It is probably due to an abnormal 

 segmentatioia of the row of mesoblast cells which form the primitive 

 ba^is for the osseous skeleton of the digit. The condition illustrates 

 Mendelian inheritance. It is not transmitted by the normal members. 

 There are thirty -six descendants of the abnormal members of the family^ 

 and fifteen of these show the abnormality. 



Development of Biliary System in Animals without Gall- 

 bladder.:!:— Richard E. Scammon has studied in this connexion the 

 lamprey, the pigeon, and the rat. 1. In the lamprey a complete biliary 

 apparatus is formed and persists throughout the larval or Ammocoete 

 stage. At the time of the transformation of the larval to the adult 

 form there is a total degeneration of both gall-bladder and ducts. 2. In 

 the pigeon the gall-bladder is developed apparently in a perfectly normal 

 way, and later, in the majority of cases at least, is completely lost. The 

 duct to which it is attached persists and grows to some size. This case 

 is complicated, however, by the presence of a larger anterior hepatic 

 duct which opens independently into the duodenum and is never 

 associated with the gall-bladder. 3. In the rat there is at most but 

 a trace of a cystic primordium in very early stage, and this soon 

 disappears. 



The author has not observed any common factors which would 



• Genetics, i. (1916) pp. 53-89. 



t Journ. Anat. Physiol., 1. (1916) pp. 177-86 (14 figs.). 



X Anat. Record, x, (1916) pp. 543-58 (10 figs.) 



