ÖFVERSIGT AF K. VETEN SK. -AK AD. FÖRHANDLINGAR 18 94, N:0 8. 347 



result of the activity of several cells, which deposit calcareous 

 salts in a liquid state in the common pseudopodial clurap, where 

 the formation of the tetrahedron afterwards takes place. On 

 account of the transparency of "pseudopodial plasni and the 

 cpacity of the granulär main portion of the cells, one gets the 

 impression that the tetrahedron is extracellular in position». . . . 

 »Thus we see that the calcifying niatrix, originated from the 

 ectoplasm of many calciferous cells, predetermines the form of 

 the increasing deposit and gives rise to the organic substance 

 in the deposit as well as to the thin coat or membrane which 

 invests it.» The above remarks may be sufficient to prove that 

 the opinion expressed by me is that the formation of calcareous , 

 deposits lias an intracellular origin, a view different from that 

 of my predecessors. Chun in his paper on the development of 

 the Auricularia-wheel reports these views of mine, but not accu- 

 rately. Thus he cites: »Er wird nämlich zwischen mindestens 

 drei Zellen in einer klaren organischen Grundsubstanz gebildet 

 und erweist sich daher von vorn herein als ein ihtercellulares 

 skeletstück, an dessen Vergrösserung späterhin eine grosse Zahl 

 von amöboiden Zellen sich betheiligt.» Farther on he continues: 

 »Während man bisher die Skeletstücke der Echinodermen im 

 Wesentlichen als inter cellulär e Gebilde auffasste» etc. . . . Seeing 

 that Chun holds that the Auricularia-wheel originates and 

 grows within a cell, we both agree in the opinion that calca- 

 reous bodies have an intracellular origin. 



With regard to the other phenomena in the development 

 of the Auricularia-wheel, there seems to be scarcely anything 

 similar observed in other Echinoderms. To sum up, Chun's 

 results are as follows: l:st The calciferous cell is globular and 

 iiivested by a definite membrane, consequently not araoeboid; 

 2:nd The cell grows rapidly, becomes flattened and its nuclei 

 increase in number; 3:rd When the cell has attained a diameter 

 of 0,03 mm., a new membrane arises inside the cell-membrane, pre- 

 senting an undulated outline and rapidly assuming the shape of 

 a Star. The hoUow rays grow longer towards the cell-membrane 



