5_ HJALMAR THÉEL: ACTIVITY OF AMOEBOID CELLS IN THE ECHINOl 51 



length, thus constituting a network of a most strange appearance. As a rule, the 



network encluding the plasmodia forms a continuous whole under the sun. 



slip. In the plasmodia, which vary greatly in shape, size, and number of pseudopodia, 



there are no traces of the primitive solitude of the cells. 



The phenomenon, which is accomplished in the remarkably short tim« 

 halfan hour, or somewhat more, is of special interest, considering that a singularly 

 favourable opportunity is offered for seeing how amoeboid cells or leuc« from 



the beginning free, change and tend to be fixed and to fuse together in ordei 

 result in the formation ot a "tissue" in many respects reminding one of the \< lly-lik<- 

 connective tissue of the early embryo in higher animals. This resemblan wies 



especially striking in those cases where the amoebocytes intercommunicate only by 

 their branches, their bodies still remaining separate. 



The best views of the plasmodia and network were obtained by treating the 

 object fixed in sublimate, Perenyi's fluid, or even alchohol with an iron-salt and stain- 

 ing it afterwards with a saturated solution of haematoxyline in water. My figures 

 arc drawn from objects stained in this manner, thus in conformity with the method 

 mentioned by Haidenhain. 



Under the cover-slip the amoeboid cells and their derivatives, the plasmodia, 

 increase mainly in circumference and by degrees become very expanded and Hatt« ned; 

 consequently they are well adapted for a successful stud)- of the structure of protoplasm. 



In the plasmodia the oval nuclei vary considerably as to their number and 

 mutual position. That portion of the protoplasm which surrounds the nuclei in a 

 greater or smaller extent is granular-looking, the granules being dark-coloured when 

 stained according to Haidenhain's method. Around the nuclei or in their vicinity, a 

 various number of larger and smaller vacuoles are to be observed in the granular 

 substance, but in other parts of the plasmodia vacuole-like bodies may also be umnd. 

 Issuing from the granular substance, another dull-coloured, almost homogenious pi 

 or spongioplasm occurs; it radiates towards the periphery and assumes the shap 

 cords, fibrils, and even specks which anastomose by their branches and constitute an 

 irregular network which, in its turn, protrudes numerous, very fine, intercommuni- 

 cating threads, thus giving rise to a very delicate reticulum, or sponge-work, the 

 meshes of which arc occupied by the clearer hyaloplasm. The granular substance 

 as well as the fibrils and cords of the spongioplann often prolong into the pseudo- 

 podia and eventually fuse together with those of other cell-. The proportion I 

 the different substances, as well as the shape and size of the fibrils, »pecks, 



and meshes, vary in different cells and plasmodia and in different parts of the proto- 

 plasm of the same plasmodium. 



