204 
always interradial. A Polian vesicle was also developed and a typ- 
ical small madreporic canal, fastened in the dorsal mesentery. It 
would be very interesting to follow the development of this organ 
during the stages beforethe appearance of the 
first ten tentacles; unfortunately the collec- 
tion does not contain these very first stages 
of the regeneration. 
The genital organs seem to develop very 
Fig. 3. Anterior end of Acti- låte. In specimens where all organs were 
nopygadifficiiis (Semper), op- near iy as we ll developed as in undivided spec- 
ened to show the regenat- 
imens, genital organs were absent or very 
ing lnuscle bands. 
l/o 
feeble, while an equally sized normal, undi¬ 
vided animal had a one centimeter long tuft. 
Long time seems to pass before the intestine comes into func- 
tion. In all the young stages the old intestine was filled with sand, 
while the new regenerating part was without any content, pale and 
collapsed. 
Regarding the age in which division takes place it seems to 
be before the animals are fullgrown. In A. difficiiis (Semper) division 
appears to occur when they have a length of 5—7 centimeters and 
in A. parvula (Sel.) a length of 3 to 4 centimeters. The maximal 
length of the first named is 10 cm, of the other one 6 cm, measure- 
ments taken on preserved specimens. 
Literature. 
W. B. Benham: Rep. on Sundry Invertebrates from the Kermadec Islands. 
Trans. New Zeal. Inst. Vol. 44. Wellington. 1912. p. 136. 
H. C. Chadwick: Notes on Cucumaria planci. Trans. Liverp. Biol. Soc. 
V. 1891. p. 81. 
W. I. Crozier: Multiplication by fission in Holothurians. Amer. Natural¬ 
ist. 1917. p. 560. 
Daly e 11: The Powers of the Creator displayed in the creation. I. 1851. p. 72. 
Ch. L Edwards: The development of Holothuria floridana Pourtalés with 
special reference to the ambulacral appendages. Journ. of Morph- 
ology XX. 1909. p. 211. 
Fr. S. Monticelli: SulT autotomia delle Cucumaria planci (B). Rendic. Ac- 
cad. Lincei. Ser. V. Vol. V f *. 1896. p. 231. 
E. Torel le: Regeneration in Holothuria. Zoolog. Anzeiger. 35. 1909. p. 15. 
