No. 609] MULTIPLICATION IN HOLOTHURIANS 



562 



vidual, which was 40mm. long, was obtained among a 

 group of 47 taken from under a large rock in April, 19 16. 3 

 The anterior end for a distance of 7 mm. from the tip was 

 light greenish yellow, with ten very feebly developed 

 tentacles ; there was a sharp line of demarcation between 

 the light yellow surface and the dark olive green of the 

 rest of the body. If H. captiva undergoes division nor- 

 mally, it can only occur in very young stages. 



"With H. surinamensis, however, the case is quite dif- 

 ferent. In Table I there are summarized results of the 

 examination of several series of these animals collected at 

 different times for this particular purpose. It will be 

 noted that in these collections from 2.5 to 16.9 per cent, 

 (on the average about 11 per cent.) of the individuals 

 show a condition of either the oral or of the cloacal end 

 which, is interpreted as representing regeneration. This 

 seems to be about the proportion of such instances which 

 is to be met with in general collecting, although numerical 

 records have been kept only in the cases cited. The 

 specimens represented in the tabulation were obtained 



TABLE I 



THE EELATIVE NUMBER OF CASES IN WHICH Holothuria surinamensis WAS 



FOUND TO BE EEGENERATING IN NATURE 



Ratio of regenerating oral to cloacal ends = 1 : 1.17. 



from one locality, Fairyland Creek, where they notably 

 abound; but the species has been collected at many other 

 stations, where also the regenerating individuals are to 

 be found in approximately the same proportion. The 



s It is known that some holothurians tend to congregate together in con- 

 siderable numbers at their tiine of breeding. Graber considered this to 

 indicate the pme^ce of a cheiricnl senFe (Delage et Herouard, 1903). 



