GYMNOMYXA. 3 



Class 1. GYMNOMYXA (SARCODINA).* 



Protozoa possessing the poiver of thrusting out pseudopodia. An 

 investing membrane is absent, or, if present, is incomplete, and'tyaves 

 a considerable portion of the protoplasm exposed. A calcareous shell, 

 or silicious skeleton, is very usually secreted. 



The body-substance, which is richly granulated, and may contain 

 pigment, contracts slowly, and sends out at the same time the 

 processes called pseudopodia; and these serve not only as a 

 means of movement, but also for the reception of nourishment. 

 The pseudopodia may be broad, lobed, or finger-like processes 

 (Fig. 2), by means of which a quick and flowing motion can 

 be imparted to the body mass; or they may be filiform radiating 

 processes (Fig. 1) ; or, lastly, they may anastomose with one 

 another, and 

 form networks. 

 A tougher, clear 

 homogeneous 

 external layer 

 (exoplasm) is 

 usually to be 

 distinguished as 

 the peripheral 

 boundary from 

 a more fluid and 

 more granular 

 internal mass 

 (endoplasm). 

 During motion 

 the former is 



, FIG. 1. Optical section through portion of the body of Actinosphaerium 



projected in Eichhornii (after Hertwig and Lesser). N nuclei in the endoplasm, 

 processes into from which the vacuolated ectoplasm is clearly distinguishable. 

 In the centre of the pseudopodia the axial thread is visible. 



which the gran- 

 ules of the latter stream more or less quickly. In the stiffer pseudo- 

 podia streams of granules are observable, slow but regular, passing 

 from the base to the extremity and vice versa. The explanation of 



* Dujardin, " Observations sur les Rhizopodes." Comptes rendus, 1835. 

 Ehrenberg, "Uber noch jetzt zahlreich lebeude Thierarten der Kreidebildung 

 und den Organismus der Polythalamien." Abhandlung der Akad. zu Berlin, 

 1839. Max Sigm. Schultze, "Uber den Organismus der Polythalamien." 

 Leipzig, 1854. Joh. Mitller, " Uber die Thalassicolen, Polycystinen und Acan- 

 thometren." 1858. E. Haeckel, "Die Radiolarien. " Eine Monographic. 

 Berlin, 1862. 



