8 ARKIV FÖR ZOOLOGI. BAND 13. N:0 25. 



though they were very crowded in the microscope chamber. 

 Otherwise did they operate, when they were in contact with 

 the true plasma-amoebocytes. » 



On the other side, I never saw any metamorphosis going 

 on in such a way as denoted by Goodrich in his paper quoted 

 above. In Ästerias rubens the bladder-amoebocytes do not 

 change form in any essential way after the removal from 

 the animal — ef. text-figure 3 {Ast. ruh.) representing a series 

 of bladder-amoebocytes fixed immediately after withdrawal 

 of coelomic fluid, and figs. 11 — 13 on plate 2 {Ast, ruh.), which 

 were drawn from cells fixed several hours after withdrawal 

 of coelomic fluid. Presuming Goodrich to be right in his 

 statement, there must exist a difference between the coelomic 

 corpuscles of Ästerias rubens and Asteracanthion glacialis 

 greater t han I can believe to be in conformity with the truth. 



According to the statement of Goodrich, no fine pseudo- 

 podia] processes should be present in fresh leucocytes of echi- 

 noderms. As shown in my paper s on Ästerias rubens and 

 Parechinus miliaris, that may be right with regard to the 

 discoidal type of plasma-amoebocytes and their nearest re- 

 latives, but it cannot be accepted as a general rule, for all the 

 coelomic plasma-amoebocytes, which are classified under the 

 type B (Parech. mil. pp. 25 — 27) are characterized by possess- 

 ing a concentrated cell-body with fine, longer or shorter pseudo- 

 podia. Here I call attention to that all the figures (except one) 

 on plates 4, 5 and 8 (Parech. mil.) are fixed immediately after 

 the removal of the coelomic fluid from the animal. The pre- 

 sence of type B, as well as of syncytia f loating in the coelomic 

 fluid of echinoderms, seems to have escaped the notice of 

 other investigators. 



Typical hyaline plasma-amoebocytes.^ 



Hyaline thigmocytes Tait and Gunn.^ 



When the coelomic fluid has been removed from the body 

 of a holothurid, the plasma-amoebocytes behave themselves 

 almost like those of asterids and echinids. However, I fre- 

 quently got the impression, that they are less numerous in 



* Théel 1919. Parechinus miliaris, pp. 10 — 27. 

 - Op. cit. 1918. 



