250 SUMMARY OF CURRENT RESEARCHES RELATING TO 



portion of the ganglion is an intricate network of fibrillar, which in 

 places is seen to be continuous from cell to cell, and with the fibrillar 

 between the nerve-cells. Tigroid-like substance is found in the nerve- 

 cells, sometimes as dense masses, sometimes as flakes or dots. Vacuoles, 

 often containing yellowish pigment, are frequently seen in the nerve- 

 cells. The simple structure, with the relatively small number of 

 association-cells, shows a very simple type of central nervous system. 



INVERTEBRATA. 



Mollusca. 

 y. Gastropoda. 



Chromosomes in Snail.* — C. F. U. Meek finds that the length of 

 the mitotic spindle, i.e. the distance between the centrosomes, is 15* 3 //. 

 at the conclusion of each primary spermatocyte metaphase of Helix 

 pomatia, and that the length of the mitotic spindle is 12 - l/x at the 

 conclusion of each secondary spermatocyte metaphase. 



The ratio between the lengths of the mitotic spindle at the conclusion 

 of the primary and secondary spermatocyte meitaphases is approximately 

 the same in Helix pomatia, Forficula auricularia, and Man ; and, since 

 these ratios are either identical or almost identical with the ratio between 

 the radii of two spheres, of which the relative volumes are the same as 

 those of the cells in question, connexion may exist between spindle- 

 length and cell-volume at this stage. 



A comparison of mitotic figures in Helix pomatia, Forficula auricularia, 

 and Man, proves that the length of the spindle in spermatocyte meta- 

 phases cannot be correlated with the volume of chromatin in the cell. 



Structure of Conus.f — H. 0. N. Shaw has made a study of Conus 

 tulipa and G. textile, and describes the structure of the teeth, the mouth, 

 the gullet, the poison-gland, the poison-duct, the salivary gland, the 

 stomach, the nervous system, and the circulatory system. In spite of 

 the difficulty of the material, it was found possible to make a number of 

 histological observations. 



Metabolism of Snail. f — W. Klihn gives an account of observations 

 on Helix pomatia, with special reference to the metabolism during the 

 winter sleep, and the periods of torpor brought about by hunger and 

 drought. During the winter sleep there is an exchange of gases both 

 through the epiphragm and through the shell. Hibernation takes 

 place even when external conditions are favourable ; a period of summer 

 torpor does not affect the need for the winter sleep. Both during 

 winter sleep and drought torpor loss of weight varies in consecutive 

 periods, and is associated with the temperature. The loss is greater 

 during a period of hunger torpor in summer than during a corresponding 



* Proc. Roy. Soc, B, lxxxviii. (1914) pp. 192-7 (1 pi.). 



t Quart. Journ. Micr. Sci., lx. (1914) pp. 1-60 (6 pis. and 12 figs.). 



\ Zeitschr. wiss. Zool., cix. (1914) pp 128-84 (9 figs.). 



