304 w. aucher. 



Ehrenb.i This form, under the erroneous name of Actino' 

 phrys sol, was long ago the subject of study by Professor 

 KoUiker/ whose account of this now widely known form, 

 subsequently enlarged by Stein^ (who correctly placed it in 

 a genus distinct from Actinophrys), is briefly referred to by 

 Schulze (1. c), and hardly nowadays needs any further 

 recapitulation here. The axile threads in the pseudopodia, 

 discovered by Max Schultze,^ are referred to above in connec- 

 tion with Hertwig and Lesser^s observations. 



Some remarks on this fine form were published by Greeif/ 

 who believed he had detected, not two only, but in reality 

 four, concentric strata in the body-substance — (1) an ex- 

 tremely thin, granuliferous stratum surrounding the whole 

 body, possessing a slow current, and continued directly into 

 the soft pseudopodial cortex ; (2) the clear alveolar stratum 

 following thereupon ; (3) a comparatively thin homogeneous 

 protoplasma-layer posed between ecto- and endo-sarc, mutually 

 separating these and surrounding like a thick membrane the 

 whole inner space; this he hence directly compares to and 

 even designates it as the homologue of the central capsule of 

 the Radiolaria ; and (4) the minutely reticulate, dark, richly 

 granuliferous endosarc. Professor Greef further regarded the 

 pseudopodial axes as spines, and thought that they penetrate 

 the "central capsule" of soft organic substance, and end 

 inwardly, in the endosai'c, with a blunt clavate extremity. 



Professor Schulze sees no reason (nor does there, I fancy, 

 really any such exist) to give up Kolliker's original view of 

 but two strata — endo- and ecto-sarc — nor does he perceive 

 Greeff''s external cortical zone, nor the assumed intermediate 

 layer. Schulze's own observations as to structure seem to 

 coincide with those of Hertwig and Lesser. The sarcode 

 surrounding the axes of the pseudopodia is but a continua- 

 tion of that forming the ectosarc, and in some very broad 

 ones even sometimes, near the base, may, like it, show 

 alveolae. Granules can sometimes be seen, carried by the 

 slow current which prevails, to pass from the ectosarc region 

 to the "cortex" of the pseudopodia and return therefrom 

 back to the ectosarc. From this it follows that Greeff's pre- 

 sumed distinct external layer has no foundation in fact. 



1 Schultze's 'Archiv,' Bd. x, p. 328. 



' * Zeitschr. f. wiss. Zoologie/ Bd. i, p. 198. 



' Stein : ' Die Infusionsthiere auf ibre Entwicklung untersucht.' (1854), 

 p. 151. 



* M. Schultze : ' Das Protoplasma der Uliizopoden und der Pflanzen- 

 zellen' (1SG3). 



^ Greeff, in ' Sitzungsbericbte der Niederrheinschen Gesellschaft fur 

 Jfatur- und Heilkunde,' Bonn, Jan., 1871. 



