24 



ARKIV FÖR ZOOLOGI. BAND 13. N:0 25. 



liaris have led me to the conviction that the coagulation- 

 l^henomena in echinoderms, to a certain degree, are due to 

 the plasma-amoebocytes and their long pseudopodia, but 

 that a fibrin-like substance plays an important part, too. How- 

 ever, I left undecided in what ways the fibrin originates. 

 From several reasons, I am obliged to leave that question 

 open, even with regard to the holothurian blood. As to the 



_,s**C^-« 



Text-figur 5. A piece of a coagulum formed within a tubular glass, into which 

 the coelomic fluid of Mesothuria intestinalis has been removed. All the strings, 

 net-work and filaments are drawn, which are visible under a moderate magni- 

 fying power (Zeiss' Ocul. 4 and Obj. 4). Amoebocytes with spherules, blood- 

 corpuscles and bladder-amoebocytes present themselves scattered or in mas- 

 ses, but the true plasma-amoebocytes are very rare. Fixed in formalde- 

 hyde in solution and stained by iron-alum hsematoxjdin. 



coagulation process that occurs in the blood of other inverte- 

 brates, and especially in crustacean blood, I refer to the ex- 

 cellent reports of Tait^ and Tait and Gunn^ 



To my knowledge, Howell^ is the first and only one 

 to draw attention to the occurrence of coagulation in holo- 



' and ^ Quart. Journ. exper. Physiology. Vol. XII, No. 1. London 1918. 

 ^ John Hopkins University Circulars. No. 43, pp. 4 — 5. Baltimore 1885. 



