NOTES ON EOHTNODERM MOEPHOLOGY. 381 



no time in making their way into the ectoderm of the recently 

 hatched larva. But unless I am greatly mistaken, these oil- 

 cells are seen in Thomson's figures of the larva while it is still 

 within the vitelline membrane j^ and if this should really prove 

 to be the case, it is a fatal argument to one part at least of 

 Vogt and Yung's theory. 



Goette ^ does not mention the exact time of their first 

 appearance, but he describes them as follows : " Zu einer 

 gewissen Zeit treten in der soust noch unveranderten Ober- 

 haut zwischen ihrer Cylinderzellen keulenformige, tief gelb 

 gefarbte, kernhaltige Zellen auf, deren dickeres Ende nach 

 aussen gekehrt ist und uicht nur die Oberflache erreicht, son- 

 dern bisweilen aus ihr hervortritt.^^ I cannot find, however, 

 that Goette ever spoke of these yellow cells as contractile, 

 as stated by Vogt and Yung ; though lower down on the same 

 page he described certain other cells in the epidermis which 

 '' sitzen mit dem dickeren kernhaltigen Ende fest an der 

 inneren Cuticula;'^ and he proceeds to say of them "da sie 

 ferner kontractil sind, so ziehen sie die letztere faltenformig 

 ein, wodurch die Oberflache alterer Larven runzelig aussieht." 

 He also gave a figure illustrating this point, in which the 

 yellow cells and the contractile cells are distinguished by 

 separate letters ; and I do not know therefore why the former 

 should be called contractile, and described as the amoeboid 

 spores of symbiotic algae by Messrs. Vogt and Yung. 



Goette prudently declined to give any opinion as to their 

 nature, but described them as occurring in greatly increased 

 numbers in the largest larvae which he examined ; while they 

 are very abundant in the more advanced Pentacrinoid figured 

 by Wyville Thomson,^ which has the bases of the arms appear- 

 ing above the radial axillaries. They are equally abundant in 

 the perisome of the mature An ted on, where they have been 



» 'Phil. Trans.,' 1865, p. 521, fig. c; pi. xxiv, fig. 4. 



2 " Vergleichende Entwickelungsgeschichte der Comatula mediter- 

 ranee," ' Arcbiv f. Mikrosk. Anat.,' Bd. xii, 1877, p. 596, Taf. xxvi, fig. 18. 



3 ' Phil. Trans.,' 1865, pi. xxvii, fig, 1. 



