184 SUMMARY OF CURRENT RESEARCHES RELATING TO 



been everywhere identified. The Palolo makes its appearance in Samoa 

 in the months of October and November, during the last quarter of the 

 moon, the time of the lowest or spring tides. Woodworth is inclined to 

 believe in some thermotropic or heliotropic reaction of the " eyes " on 

 the epitokal part of the worm. The " Palolo time " in Samoa embraces 

 three succesive days. During these days another Annelid — Lysidice 

 falax Ehlers, L. viridis Gray — exhibits phenomena similar to those of 

 the true Palolo. 



Some Woods Hole Pelagic Polychgeta.* — J. Percy Moore points out 

 that the pelagic Annelid fauna of southern New England has received 

 but little attention. He describes some forms new to the region— 

 Amphinome pallasii Quatrefages, Hvpponoe gaudichaudi Aud. and M.E., 

 Drieschia pellucida sp. n., and Tomopteris kelgolandka Greef. 



Distribution of Oligochseta.f— K. Bretscher has made a special 

 study of the distribution of earthworms in Switzerland, where there 

 are sixteen 'endemic species. A great deal depends on the degree of 

 humidity and the atmospheric conditions, as is shown by considering the 

 rainfall records. 



Negative and Positive Phototropism of the Earthworm.}— G. P. 

 Adams finds that the phototropism of AUolobophora fmtida changes 

 according to the intensity of the light. The negative phototaxis, very 

 marked with intense illumination, gradually decreases as the intensity is 

 lessened. Finally, the earthworm shows itself positively phototactic. 

 This agrees obviously with the habits of the animal in nature, for it hides 

 from the sunlight, but is drawn to the weak nocturnal light. 



Regeneration in Lumbriculus variegatis.§— P. Iwanow compares in 

 detail the regeneration of trunk-segments and head-segments in this 

 worm. We can only allude to a few results. The gut is formed 

 similarly in both, by the backward or forward growing of the old gut 

 until it meets a minute proctodreal or stomodaal invagination. The new 

 epidermis differentiates early into a new growing epithelium and into 

 large sub-epithelial " germ-cells," which form nervous tissue and external 

 musculature. The mesoderm of the trunk-segments arises from special 

 indifferent "germ-cells," but in the head-segments the material for 

 mesoderm regeneration is afforded entirely by derivatives of the " germ- 

 cells " of the trunk, especially from the somatic wall. The muscle 

 elements in the head arise wholly from muscle-cells of the old mesoderm ; 

 the connective tissue cells come mainly from leucocytes or peritoneal 

 cells. Thus the secondary mesoderm in the head-segments does not 

 form chloragogen cells or nephridia. 



Experiments in Jlolosoma hemprichii.|| — Antonin Stole notes that 

 this naid has normally six double-pairs of bundles of seta?, and that its 

 asexually-produced progeny show the same number. Various parts of 



* Proc. Acad. Nat. Pci. Philadelphia, 1903, pp. 793-S01 (1 pi.). 



t Biol. Centralbl., xxiii. (1903) pp. 634-9 (1 map). 



X Amer. Jouru. Physiol., ix. ((1903) pp. 26-34 (2 fi<rs.). See Zool. Centralbl. xi. 

 (1904) p. 33. 



§ Zeitschr. wiss. Zool., Ixxv. (1903) pp. 327-90 (2 pis.). 



|| Arch. Eutwickmech., xv. (1903) pp. 638-68 (26 figs.). Sec Zool. Centralbl. x. 

 (1903) pp. 878-9. 



