SOOLOGY AND BOTANY, MICROSCOPY, ETC, 953 



Excretory Organs of Criodrilus.* — Dr. E. S. Bergh describes the 

 ontogeny of the excretory organs in Criodrilus. They arise entirely in 

 the somatic mnscle-plate, without any relation to or connection with the 

 rudiments of the adjacent segments. Funnel, coil, and terminal portions 

 are differentiated from a common rudiment. The funnel is formed 

 chiefly from a cellular material, derived from the divisions of the funnel 

 cell, and its cavity arises from the subsequent separation of the cells. 

 The lumen of the coiled portion arises from fusion by vacuoles appearing 

 within the cells. The terminal portion bores in between the epidermic 

 cells, and breaking through forms an external aperture. 



After a chapter devoted to a critical review of the results reached by 

 Kowalewsky, Kleinenberg, Whitman, Hatschek, Yejdovsky, and Wilson, 

 the author passes to describe the pair of provisional excretory organs 

 which are present in Criodrilus embryos before the segmental organs 

 are established. The pair of primitive kidneys consist of perforated 

 cells, and form white strands, very readily seen, though hitherto over- 

 looked. They have their blind beginning beside the oesophagus, and in 

 the head-cavity lie close to the epithelium of the gut. From their origin 

 they extend backwards, arching towards the back, but bend again 

 ventrally, and open to the exterior on the side of the body about the 

 middle of its length. 



$, Nematlielraintlies. 



Abnormal Ova of Ascaris megalocephala.f — M. A. Lameere has 

 found two female specimens of Ascaris megalocephala, in which the ova 

 have retained the club-shaped form which they ordinarily have only in 

 the upper part of the oviduct. Most of these eggs were non-fecundated. 



The external hyaline layer becomes thickened at the slender end of the 

 cell ; in the neighbouring region the protoplasm is clearer than in the 

 rest of the egg ; on each side of the handle of the club there is a con- 

 striction which corresponds to a circumference which bounds a surface 

 that is distinctly folded. This region clearly corresponds to the part 

 which constitutes the primitive form of the oviducal eggs. It is in 

 that part that, in the first period of maturation, when the eggs begin to 

 be gradually ellipsoidal in form, there is a groove in which the polar 

 disc is differentiated. The author believes that the germinal vesicle 

 tends to advance in a direction opposite to the pole of impregnation. 



Heterodera Schachtii.:]: — M. Willot points out that, like Dr. Steubell, 

 he has recommended the use of sea-salt as a means of killing this nema- 

 tode. Curiously enough their objects were different, for M. Willot was 

 seeking what he calls a nematocide, while the German naturalist was 

 trying to keep the worms alive, and did not see the bearings of his 

 observations on economic husbandry. 



y. Platyhelmintlies. 



General Sketch, of the Treniatoda.§ — Under this title Mr. W. E. 

 Hoyle has reprinted, with additions, his article on the Trematoda from the 

 ninth edition of the ' Encyclopaedia Britannica.' The ordinary historical 



* Arbeit. Zool.-Zoot. Inst. Wiirzburg, viii. (1888) pp. 223-48 (2 pis.). 



t Bull. Acad. R. Sci. Belg., Ivii. (1888) pp. 9S0-i (1 pi.). 



X Comptes Eendus, cvii. (1888) pp. 507-9. 



§ Svo, Edinburgh, 1888, 19 pp., 4 pis. of woodcuts. 



