ZOOLOGY AND BOTANV, BIN ROSCOPY, ETC. 625 



etc., made by the 'Poseidon' (1902-10). Particular attention is 

 devoted to the sexual conditions in Nereis diversieolor, one of the 

 interesting facts noted being the occurrence of a Palolo-like swarm of 

 headless worms in Kiel Harbour. 



Papillomatous Neo-formation in an Annelid.*— P. Mesnil and 

 M. Caullery describe in Potamilla torelli Mlmg. what seems to be the 

 first recorded occurrence of a tumour in an Invertebrate. There are 

 papilloma-like proliferations of the mesoderm, forming bud-like growths 

 on the wall of certain segments and extending inwards, somewhat like 

 false septa. In most of the modified segments there is a parasite, 

 Haplosporidium potamillse, and this may start the new growth. If it 

 does, it disappears in some cases, for some of the growths showed no 

 trace of parasite. 



New Species of Ctenodrilus.t— I wan Sokolow describes a new 

 Ctenodrilid from the lancelet sand at Naples. It occurred in five 

 different forms. In its shape, bristles, number of segments, and mode 

 of division it is nearer to Vaillant's genus Zeppelin/a than to Criodrilns, 

 and the author calls it Zeppelinia branchiata sp. n. There are 25 to 30 

 segments ; the bristles are long and thread-like (2 to 3 in a bundle) ; 

 the heart-body is intense scarlet or olive-green ; the supra-< esophageal 

 ganglion projects strongly into the cavity of the head-lobe ; the atokous 

 form has two eyes, a ciliated wreath on every trunk segment, and pairs 

 of gills on many. New individuals are usually formed from several 

 maternal segments. The new formation of the anterior and posterior 

 ends usually occurs after the separation off of the new individual. 



Nematohelminthes. 



Potency of Blastomeres in Ascaris.J — Th. Boveri enquires into the 

 potency of the blastomeres when the cleavage has been modified from 

 the normal, e.g. when dispermy has occurred, or when the ova have been 

 rotated in a centrifugal machine. In the latter case some of the eggs 

 divide into two similar blastomeres by a cleavage plane at right angles 

 to the stratification induced by the rotation. These two blastomeres 

 develop in a precisely similar way. Each of them corresponds to the 

 first " Stamm-Zelle " in the segmentation of a normal ovum. The 

 companion of this first " Stamm-Zelle," known as the first primitive 

 somatic cell, has quite disappeared as such. 



Microfilaria from a Fowl.§ — Berke gives a description of a " micro- 

 filaria," very abundant in the blood of the liver of a domestic fowl in 

 Cameroon. Associated with it in the peripheral blood, but not in the 

 liver, were numerous straight or curved rod-like bodies, the significance 

 of which is discussed. 



Plasmic Reduction in Spermatogenesis of Ascaris megalocephala.|| 

 Marc Romieu finds that the spermatid undergoes two successive cyto- 



* Comptes Rendus, clii. 1911) pp. 628-31. 



t Zeitschr. wiss. Zool., xcvii. (1911) pp. 546-603 (3 pis.). 



; Festschrift R. Hertwig, iii. (1910) pp. 215-92 (4 pis. and 16 tigs.). 



§ Centralbl. Bakt. Parasitenk., Lviii. (1911) pp. 326-30 (1 pi.). 



| Comptes Rendus, clii. (1911) pp. 223-5. 



