THÉEL, THE AMOEBOCYTES BY ECHINODERMS. 35 



arrangement of the calcareous plates of asterids and echi- 

 nids etc. and the syncytial net-work which becomes formed on 

 the glass, either af ter removal of coelomic fluid from the 

 animals into a microscope-chamber, or after a cover-glass 

 having been allowed to rest in the coelomic cavity of the living 

 animal. Furthermore, it ought to be remembered that the 

 calcification of the larval spicules of echinids begins within a 

 common plasma of three or more amoebocytes having fused 

 so as to form a syncytial centre of calcification. 



4. The calciferous amoebocytes operate in different man- 

 ner in producing quite different crystal-forms in the same 

 animal and under quite the same conditions. Therefore, the 

 mother-cells themselves must be considered to represent 

 distinct species or varieties. For I cannot t hink that the 

 same kind of cells — under quite the same conditions of life — 

 could produce crystals under the form of rhomboids, prisms, 

 st ars, spicules etc. 



5. The meaning of the coelomic calciferous cells is not 

 easily decided. If present in greater quantities, I should 

 propose them to lodge reserve-material for repairing lesions 



L of the skeleton. 



