14 



ARKIV FÖR ZOOLOGI. BAND 13. N:0 25. 



....>f-_. 



W 



7 



Text-figiire 3. Bladder-amoebocytes, 

 fixedin Perényi"s solution, stainedand 

 mounted in balsam, 1 =: a cell from 

 Mesoihuria, drawn under different fo- 

 cussing and presenting the bladders in 

 two superposing planes; 2-7 = cells 

 from Psolus; 2 = a cell with the blad- 

 ders in two superposing planes; 3 = 

 the same; 4 = two different cells; 5-7 

 = a cell with the bladders in three 

 superposing planes; diameter varying 

 from 13,6 ix to 15,2 u. 



Owing to the powerful muscles 

 of the body-wall, the animals 

 possess a very high capability 

 of rapid contraction, resulting 

 in a violent pressure of the 

 body-wall towards the intestinal 

 tiibe with the effect, that the 

 coelomic cavity raj)idly dimin- 

 ishes and the viscera become 

 disordered, or even broken. This, 

 in its tiirn, causes, that the coe- 

 lomic fillid becomes foul from 

 sordes and cells torn off from 

 the shattered tissues. 



As to the general appear- 

 ance of the bladder-cells, it bears 

 a close resemblance to that of 

 the same cells described and 

 figured in my accounts on Aste- 

 rias rubens and Parechimts mili- 

 aris} Nevertheless, there seems 

 to exist a small difference, the 

 bladder-amoebocytes of the ho- 

 lothurians seemingly being de- 

 void of pseudopodial processes 

 and membranes. 



To sum np the general re- 

 sults of my studies on the cells 

 in question, the following re- 

 marks may be made: 



1. — The bladder-amoebo- 

 cytes seem to have escaped the 

 notice of previous investigators 

 of the coelomic fluid of echino- 

 derms. Even Goodrich^ (1919) 

 does not mention them in Aste- 

 racanthion glacialis, though, to 



^ See Asterias rubens. pp. 15 — 26; Parechinus miliaris, pp. 27 — 30. 

 ^ Op. cit. 



