6 ARKIV FÖR ZOOLOGI. BAND 13. NIO 25. 



In this connection I may be allowed to devote attention 

 to the chief results recorded by Goodrich^ in his paper on 

 »The pseudopodia of the leucocytes of invertebrates », which 

 was published somewhat låter than my own account of the 

 amoebocytes of Ästerias rubens. On page 25 he says as follows: 

 »The leucocytes of the blood or coelomic fluid of the invertebrate 

 Coelomata are provided with more or less extensive membranous 

 processes of cytoplasm. The freely-projecting pseudopodia 

 usually described are either figured from optical sections of the 

 folded membranes or from cells which have produced them 

 under abnormal conditions. These fine pseudopodia may 

 be present on cells in fluid withdrawn from the body and which 

 has been allowed to stånd, and are probably derived from pre- 

 existing membranes. The delicate motile membranous folds 

 are usually expanded in the normal fluids of the living animal. » 



This statement of Goodrich's is based on studies of the 

 leucocytes of several different types of invertebrates, f. inst. 

 Arenicola, Lumbriciis, Ostrea, Mytitus, Carciniis, Astacus, 

 Eupagurus and Ästerias glacialis, too. Considering that my 

 studies are limited to the amoebocytes of echinoderms alone, 

 I am unable to pronounce an opinion on the behaviour of the 

 cells of other types. On account of this, the follomng parallel 

 between our respective results concerns the echinoderms alone. 

 We evidently agree in part, but differ nevertheless in several 

 respects. In order to manifest the differences of our opinion, 

 it may be enough to render in translation some excerpts from 

 my papers, and to refer to their plates and text-figures. 



Firstly, I have distinguished between two kinds of amoe- 

 bocytes in the coelomic cavity of Ästerias rubens, white or 

 hyaline plasma-amoebocytes, and bladder-amoebocytes (= blås- 

 amoebocyter) — ef. text-figures 3 (Ast. rub.) and 4 {Parech. 

 mil.), while Goodrich has accounted for one alone. However, 

 the two kinds of amoebocytes are in reality very dissimilar, 

 the bladder-cells not being flattened, nor spread out on the 

 surface of the glass, but they remain thick and compact with 

 the bladders lying in several superposed layers. In spite of 

 these striking differences, I nevertheless (Ast. rub. pp. 18 and 

 26) gave expression to my hesitation whether they may be 

 derived the one from the other, and I also alluded to that 



^ Op. c it. 



