16 ARKIV FÖR ZOOLOGI. BAND 13. NIO 25. 



quently that my knowledge of them is very defective. As far 

 as my experience goes, all the holothurids are in possession 

 of this kind of amoebocytes. As a rule, they are white and 

 hyaline, and characterized by possessing large, refractile gra- 

 nules or spherules. Some of the cells are loaded with spherules, 

 others again contain a smaller number of them. In the same 

 cell all the spherules are almost uniform in size, but in different 

 corpuscles they can have different dimensions. On the whole, 

 this kind of cells and their behaviour closely resembles those 

 in Parechinus miliaris, wherefore I cannot do anything better 

 than to ref er to my former account — ef. Parech. mil., pp. 30 — 39. 



It is a well-known fact that the echinids, besides white 

 amoebocytes, possess a lot of coloured ones. In the holothurids 

 the white corpuscles are thoroughly predominant, though, 

 there also, species are to be met with which are characterized 

 by the possession of both white and coloured corpuscles. 

 Thus, for inst., Labidoplax buskii makes an exception by 

 lodging cells with hyaline granules together with such ones 

 which contain red-pigmented granules, both kinds being nearly 

 equal in number. But the coloured cells are somewhat smaller, 

 measuring about 11,4 [j. in length. — ef. pl. 1 fig. 1. There is 

 just a similar case in Stichopus tremula, but here the coloured 

 cells are very scarce and minute, reaching in length from 

 7,4 {1 to 11,4 [j.; the white corpuscles, on the contrary, measure 

 from 17,1 tx to 22,8 \l in length. 



As problematic, I denote such coloured corpuscles which 

 have a tinge of brown and which may be found in Cucumaria 

 elongata and hyndmani, Thyone fusus and Psolus pharäapus. 

 Very likely a part of them may be considered as strangers 

 which have been pushed into the coelomic cavity by means 

 of ruptures of the intestines, caused by violent contractions 

 of the hurt body-wall. 



Red blood-corpuscles. 



As far as I know, Semper's work (1868)^ was the first 

 to throw light on the existence of red blood-corpuscles in the 

 holothurids. On page 127 he stated that: »Bei Cucumaria 

 canescens finden sich ausserdem [crystals] noch runde, grosse, 



' Reisen im Archipel der Philippinen, II, 1. Holothurien. Leipzig 1868. 



