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



several refractile granules, which by various focussing exhibit 

 a tinge of white, red or brown. The roundish nucleus is obscure 

 in living cells, presenting itself as a light spöt. 



If one is steadily kept under observation from the time 

 the blood-cell escapes from the circulation, it can be seen, 

 first of all, to undergo-certain changes in form. The cell seems 

 to swell a little, and its contour to become erose or wavy; 

 subsequently, it assumes an irregular shape by sending forth 

 roundish protuberances (pl. 5, figs. 14 and 17), which appear 

 to separate from the mother-cell resulting in the formation of 

 free, hyaline particles in the ambient fluid — ef. text-figure 4. 

 I suppose this to be taken for an abnormous process, though 



Text-figure 4. Red blood-corpuscles of Thyone jusus in a state of cytolysis. 



there is plenty of such particles especially in the polian vesicle, 

 where their diameter measures from 2,6 [x to 5,i {jl. At first 

 sight, one gets the impression that the process in question has 

 something to do with amoeboid movements, but it ought 

 probably to be looked upon as a case of cytolysis. 



When treated with osmic acid or 40 % formalin and stained 

 by HErDENHAiN's iron-alum haematoxylin method, the nucleus 

 of the cells becomes distinctly conspicuous. The fixation 

 with formalin has the effect of bringing forth a number of 

 light blebs (pl. 5, fig. 16). 



In this connection it may be noted, that the polian vesicle 

 lodges a number of hyaline fusiform bodies of from 3,8 {i 

 to 19 {X in length; every gradation in size between the two 

 extremes may be met with (pl. 5, fig. 18). They may very likely 

 be looked upon as shatters of tissues; the presence of such 

 mysterious bodies in other holothurid species has already 

 been noted several times. 



