34 SUiMMAKY OF CURRENT RESEARCHES RELATING TO 



relatively gigantic compared with their relatives in shallow water, as 

 may be well illustrated by the sea-slater, Batliynomus doaderleiiii, and 

 even by some very large Foraminifera. The chief cause is probaljly 

 that the stillness of the great depths allows of great estensiou of body 

 without risks. J. A. T. 



Prolongation of Life and Vigour. — W. Harms {Zooloy. Anzpifjrr, 

 1020, 51, 161-<s). In some worms, e.g. the Palolo worm, and in other 

 cases, there is a natural evasion of senile degeneration by surrendering 

 a large part of the body. In Hydroides an artificial removal of the 

 ageing abdominal segments gives the worm a new lease of life. Another 

 method is the artificial implanting of testes, which Harms found to be 

 efficacious in guinea-pigs. After sexual vigour had quite waned it was 

 restored by ingrafting a piece of young testes. The ' restoration of 

 sexual vigour lasts for some time. J. A. T. 



• 

 Tunicata. 



Test Vesicles in Tunicates. — Caswell Grave {Proc. Amer. Soc. 

 Zool. in Anat. Record, 1!)20, 17, 350). The fully developed tadpole 

 larva of Amaroucium constellatum has about sixty spherical multicellular 

 test vesicles. They arise as elongated evaginations from four median 

 sagittal elevations of the ectoderm, but they become free in the larval 

 tunic and resemble Echinoderm blastulffi. When the metamorphosis 

 beaius thev migrate to the external surface of the tunic and begin to 

 proliferate tunic material. They are concerned with the formation and 

 I'egulation of the common tunic of the colony, and continually produce 

 new cells. They do not increase or decrease in number during the life of 

 the colony. No structural connexion with ascidiozooids was made out. 

 The vesicles are organs of the colony as a whole, but they are all derived, 

 from the individual by which the colony is founded. They persist, 

 however, long after the primary zooid has lost its identity. J. A. T. 



IN VERT E BE, AT A. 



MoUusca, 

 a. Cephalopoda. 



Regeneration of Arm of Octopus. — Mathilde M. Lange (Jouni. 

 E,vper. Zool., 19:^0, 31, 1-40, 8 pis.). AYhen an arm of Octo'pus vuhjark 

 is cut off the edges of the wound curl inwards; the axial nerve pro- 

 trudes ; bleeding sets in after five to six hours ; the pi'otrusion of the 

 ^ axial nerve disappears ; an epithelial healing occurs. A knob appears 

 with a thin rod-like appendage. New suckers ajjpear on the regenerated 

 piece proper, and at the obtuse end of the arm stump. The first new 

 chromatophores appear about three or four weeks after operation. All 

 new tissues, with the exception of the dermal connective tissue (which 

 is- probably developed from the primary blastema due to the agglutinated 

 blood-corpuscles) are produced in regeneration from the pre-existing. 

 tissu'.'S of the same kind. J. A. T. 



