

FESTSKRIFT FÖR MI.LJEBORG 



When let alone for several hours under the cover-slip and afterwards sui- 

 tably fixed and stained, the plasmodia offer a countless number of fine, long pseu- 

 dopodia, and their peripheral sponge-work presents itself as a very thin, transparent 

 i between the bases of the processes. 



Considering that there are good reasons for the suspicion that views ob- 

 tained under the cover-slip arc peculiar to the abnormal condition under which the 

 amoebocytes were operating, I undertook to verify these phenomena by arranging 

 some other experiments. 



Thus, for instance, 1 made a slit near the apical pole in the shells of some 

 large specimens of Echinus esculentus, and inserted a circular cover-slip in the peri- 

 visceral fluid. Knowing the uncommon power of resistance and regeneration of the 

 Echinoderms, there is no ground for the supposition that the animals were hurt in 

 such an essential way, that the amoebocytes could be induced to operate in a manner 

 deviating from the normal one. 



While in some cases the slips were allowed to pass down into the coelomic 

 cavity and to take an almost horizontal position there, in other cases I attached im- 

 portance to letting the slip remain hanging vertically in the corpusculated fluid, the 

 slip being kept from sinking by the pressure of the lips of the fissure. 



After the lapse of half an hour or slightly more, the cover-slip was carefully 

 r< moved and examined, whereupon it proved to be covered all over with a layer of 

 corpuscles. In both cases, whether the cover-slips were hanging vertically or had 

 sunk down into a horizontal position, the result was the same. When fixed and 

 stained, the object presented itself as a meshwork of cells and plasmodia fused toge- 

 ther by longer or shorter pscudopodia just as has been noted to take place under 

 the cover-slip in the drop of perivisceral fluid watched with the microscope. 



It is, however, worthy of notice that there really exist some trifling dif- 

 I' rences, probably due to the varying conditions under which the cells operate, in the 

 <>ne case compelled by the cover-slip to extend mainly in one plane, in the other 

 case quite free to move and enlarge in all directions. In their natural, free state, the 

 • . 11-, chiefly arrange themselves in a rather thick "reticular tissue" and the different 

 substances of their protoplasm, when examined with a high magnifying power, do 

 not become apparent in such an obvious manner as when the cells arc forced to 

 spread out in one plane under a cover-slip. In both instances, however, the amoe- 

 bocytes join cither indirectly by means of their pscudopodia (network) or by direct 

 fusion (plasmodia). 



( >n purpose to get another chance of studying the amoeboid cells and their 

 mod. ol operation in a free state, I repeated many times the experiments previously 



