GROMIA 



735 



generally, was first established by Dr. Wallich. The sarcode : body 

 of this animal is encased in an egg-shaped, brownish-yellow, chitiiious 

 envelope, which may attain a diameter of from ^th to j^th of an 

 inch, looking to the naked eye so like the egg of a zoophyte or the 

 seed of an aquatic plant, that its real nature would not be suspected 

 so long as it remained quiescent. The 'test' has a single round 

 orifice, from which, when 

 the animal is in a state 

 of activity, the sarcodic 

 substance streams forth, 

 speedily giving off ramify- 

 ing extensions, which, by 

 further ramification and 

 inosculation, form a net- 

 work like that of Lieber- 

 kuehiiia. But the sarcode 

 also extends itself so as 

 to form a continuous 

 layer over the whole ex- 

 terior of the 'test,' and 

 from any part of this 

 layer fresh pseudopodia 

 may be given off. By 

 the alternate extension 

 and contraction of these, 

 minute protophytes and 

 protozoa are entrapped 

 and drawn into the in- 

 terior of the test, where 

 their nutritive material 

 is extracted and assimi- 

 lated ; and if the ' test 

 (as happens in some 

 species) be sufficiently 

 transparent, the indi- 

 gestible hard parts (such 

 as the siliceous valves of , 

 diatoms, shown in fig 

 571) may be distinguished 

 in the midst of the sar- 

 codic substance. By the 

 same agency the Gromia 

 sometimes creeps up the sides of a glass vessel. In the intervals of 

 quiescence, on the other hand, the whole sarcodic body, except a 

 film that serves for the attachment of the test, is withdrawn into its 

 interior. 



Another example of the reticularian group is afforded by the 

 curious little Microgromia socialis (fig. 572), first discovered by Mr. 

 Archer, and further investigated w r ith great care by Hertwig, 1 which 



FIG. 571. Gromia oviform is, with its 

 pseudopodia extended. 



'\jeber Microgroinia,' in Arcliiv fur Mikr. Anat. bd. x. Supplement. 



