[Reprinted from THR: AMERICAN NATI'RAUST. Vol. 1. 1., September. 1917. 



MULTIPLICATION BY FISSION IN 

 HOLOTHUBIANS 1 



DR. W. J. CROZIER 



THEEE is to be found in various text-books the state- 

 ment that certain pedate holothurians are capable of 

 spontaneous transverse division, each part so formed 

 producing a new individual (Lang, 1894, p. 1095; Morgan, 

 1901, p. 144). This opinion seems to be based, so far as 

 I can learn, upon the observations of Dalyell (1851, p. 

 74; PI. XIV), although Morgan says that "more recent 

 observers have confirmed this discovery.' 1 Chadwick 

 (1891), also, found small individuals of Cucumaria planci 

 to undergo self-division, and in one instance the posterior 

 portion so formed also divided. These are records of 

 division in holothurians which were being kept in small 

 aquaria, and there lias been no evidence, so far as I am 

 aware, going to show that self-division of adult pedate 

 holothurians is a method of propagation among these 

 animals in their normal surroundings. Hence the possi- 

 bility of non-sexual reproduction in this way is usually 

 stated with reserve (cf. Lang, 1894). 



In other classes of echinoderms (aside from echinoids) 

 the expedient of reproduction by fission is of course not 

 unusual; but in ophiuroids and in such starfishes as 

 LincMa (Clark, 1913) and Coscinasterias (Crozier, 1914), 2 

 we are dealing with the division or fragmentation of a 



1 Contributions from the Bermuda Biological Station for Besearch, No. 66. 



2 I have been able to secure further evidence regarding the fragmentation 

 of Coscinasterias (Asterias} tenuispina (Lam.), which proves conclusively 

 that the rules previously deduced (Crozier, 1915a) regarding this process 

 are indeed valid. This evidence will be published in connection with a de- 

 scription of experiments on the direction of progression in Coscinasterias. 

 The presence of great variation in ray-length, as well as of a variable num- 

 ber of madreporites, gives an opportunity to test out in this species the 

 validity of certain ideas concerning "physiological polarization" in as- 

 teroids. 



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