66 Miscellaneous. 



is brought back, by the contraction of the embryonic band, towards 

 the posterior pole. It is at this moment that the anus and the pos- 

 terior intestine are formed, by an invagination of the ectoderm at 

 the extremity of the tail. The posterior intestine, as it lengthens, 

 passes between the two polar masses and separates them from each 

 other. Lastly, at the moment of hatching, the larva possessing all 

 its organs well formed, it is easy to appreciate, from the relations 

 and structure of these masses, their significance in the organism. 

 They are situated in the ninth segment of the body, on each side of 

 the digestive tube, at the level of the junction of the posterior 

 with the middle intestine. An epithelial membrane then surrounds 

 each mass and is produced at its two extremities into a slender fila- 

 ment. Finally, in the interior of the mass the nuclei have multi- 

 plied. From all these characters it is impossible to mistake that we 

 have to do with the generative organs of the animal. These then, 

 as we hope we have demonstrated, have their origin in the polar 

 cells. 



From this mode of development some interesting consequences 

 follow with regard to the general morphology of the reproductive 

 organs. We have first of all their very early formation, precedin 

 that of all the other organs of the embryo, and indeed even that of 

 the embryo itself in its most rudimentary form, the blastoderm. 

 We have then the community of origin, not only of the male and 

 female sexual products, but of these and of the embryo. We may 

 consequently say that the ovule, the sperm atozoid, and the embryo 

 have as their common author the fecundated egg ; but while the 

 latter is capable of being directly developed, the former two only 

 acquire the aptitude for development by their union in a new fecun- 

 dation. — Comptes Hernias, November 13, 1882, p. 927. 





On Tarriform Castings of 'Earthworms in France. 



By M. E. L. Tboitessart. 



The author observed in gardens in the neighbourhood of Augers, 

 along with numerous worm-casts of the ordinary shape, a great 

 quantity of tower-like castings, exactly similar in form and size to 

 that figured by Darwin in his book' on earthworms, and ascribed by 

 him to an exotic species of Perieliceta naturalized in the neighbour- 

 hood of Nice. 



These turriform worm-casts were about 2 or 3 inches in height, 

 and about 1^- inch in mean diameter ; some were more regular than 

 indicated by Darwin, but formed in the same manner, of thick coils „ 

 of an argillo-calcareous material, black at the moment of production, 

 but becoming light yellowish grey in drying. The earthy matter 

 was strongly agglutinated by a mucus, and resists the rain for a 

 considerable time. All the towers were traversed by a cylindrical 

 passage moulded on the body of the worm, and terminated above in 

 a cone at some millimetres from the apex of the tower. In most 





