184 SUMMA.RY OF CURRENT RESEARCHES RELATING TO 



ing ova. Besides epididjmes and vasa deferentia there were typical 

 oviducts developed for about a third of their lengths. Xo vasa efferentia 

 were to be seen passing from testes to epididymis. There was on the 

 dorsal portion of one of the kidneys an embedded mass of almost 

 fully grown ova surrounded by folUcular cells. The animal must have 

 been physiologically sterile. J. A .T. 



Sex Determination in Mammals.— S. Monckton Copeman {Proc. 

 Zool. Soc, 1919, 433-5). Rabbits and some other mammals (pigs, cats, 

 guinea-pigs, mice) were used for experimentation. Semi-castration or 

 semi-spaying (affecting the gonads of one side) and ligature of vas 

 deferens or uterine cornu (on one side) was effected ; but there was no 

 demonstrable effect on the sex of the offspring. The number of 

 experiments made is not noted, but it is stated that the few cases (four) 

 of unisexual families (i.e. all male or all female) which were obtained 

 were shown by further experiment to be fortuitous. J. A. T. 



6. Histology. 



Changes in Nucleolar Substance during Mitosis. — J. Benoit (C. 

 R. Soc. Biol., 1919, 82, 1431-3). A study of spermatocytic mitoses in 

 mice. After the prophase the nucleoli seem to give rise to nucleoluli, 

 which spread themselves in the nuclear area. These nucleoluli condense 

 and apply themselves to the spireme thread. Each doubles into two 

 daughter-granules, which dispose themselves at the ends of the chromo- 

 somes when these are constituted, and migrate with them to the 

 daughter-nuclei. There they form by coalescence a daughter-nucleolus, 

 whose substance is directly due to the parent-nucleolus. There is a 

 nucleolar division as meticulous as the division of the chromatin. 



J. A. T. 



Varieties of Cartilage. — Ed. Retterer (C. R. Soc. Biol., 1920, 83, 

 21-4). Hyaline cartilage is preceded by a stage in which the clear 

 cells are not separated by any matrix. This epithelioid cartilage passes 

 into hyaline cartilage by a thickening of the partitions betAveen the 

 cells. This may pass into bone. The sub-cuboid nodule of the tendon 

 of the long lateral peroneal muscle is connective or fibrous in children 

 and sedentary people ; it is vesiculo-fibrous in most adults ; it is trans- 

 formed into a cartilaginous or bony sesamoid in those who perform 

 repeated energetic movements with their legs. In arboreal monkeys this 

 sesamoid passes through a stage of hyaline cartilage and ends as bone. 

 Hereditary predispositions count for something, but the stage which the 

 supporting tissue reaches is in direct relation to the frequency or the in- 

 tensity of mechanical excitations. J. A. T. 



Development of Mastocytes in White Rat. — E. Laguesse {C. R. 

 Soc. Biol., 1919, 82, 1415-7). Mastocytes (Mastzellen) are very abun- 

 dant in the newly-born rat, and it seems clear that this crop is due to 

 the transformation of fixed connective tissue cells. They may arise 

 from any mesenchymatous cell. In certain tissues which retain in 



