ÖFVERSIGT AF K. VETENSK.-AKAÜ. FÖRHANDLINGAR 18 94, N:0 8. 351 



become extended into long slender filameuts which give ofF fine 

 branches and anastomose with eacli otlier as well as with the 

 protrusions of other cells, thus giving rise to a network with 

 finer and wider meshes. The pseudopodia are incessantly chang- 

 ing, the look of a cell at one moment being quite diflferent from 

 that at another. Presently the pseudopodia begin to withdraw 

 again causing a gradual disappearance of the network, and si- 

 multaneously other protrusions are sent out from other parts of 

 the cörpuscle constituting new meshes and evidently also new 

 Communications with cells in the neighbourhood. But while 

 these changes are going on, the main portion of the absorbent 

 cell is by no means immovable. When a coarser Pseudopodium 

 has been protruded, it often extends itself further forcing the 

 granulär main portion of the cell to change its place and to 

 pass gradually into the protrusion. 



When a cell begins to exercise its absorbent influence on a 

 calcareous body, for instance a spicule, it strains to extend and 

 flow round and över it so as to take it whole into its proto- 

 plasm, and hence the granulär main portion of the cell moves 

 incessantly, gliding slowly along the swallowed spicule until 

 nothing remains of it. During this process the pseudopodia are 

 continuously withdrawn and given out again, proving the plasm 

 to be in a state of laborious activity. 1 have never seen the 

 operative cell escape the spicule till the absorption of it is com- 

 pleted. Seeing that the attacked calcareous particle is often of 

 considerable size as compared with the amoeboid cell, one is led 

 to'- suppose the latter capable of dissolving an unexpectedly large 

 quantity of salts and of keeping them in fluid form evidently 

 without their solidifying in the form of granules or other cal- 

 careous particles within the plasm. However, it seems to me 

 more likely that the dissoived salts are transferred gradually 

 through the pseudopodia to the cells in the neighbourhood which 

 either raay retain them until necessity requires otherwise or use 

 them immediately as materials foi' building up new calcareous 

 bodies or organs essential for the growing Echinoderm. 



