PROTOZOA. 



ratus, by whose aid the animal can transport itself from place to place, 

 but with such extreme slowness that its movements are hardly per- 

 ceptible. The locomotive filaments thus displayed are perceptible by the 

 naked eye, their length being, when fully extended, four or five times 



1. Gromia oviformis, with the rhiziform tentacles displayed. 



2. Filaments fused together into a kind of network. 



the transverse diameter of the body ; still they exhibit in their interior 

 no appearance of organization, but resemble so many threads of molten 

 glass. When protruded, each of these filaments, at first simple and of 

 equable diameter through its entire length, soon begins to elongate itself 

 in a very mysterious manner, moving in different directions, as though 

 seeking some basis of support. As the elongation of the filament con- 

 tinues, apparently owing to a constant influx of new material into its 

 substance, it is seen to give off here and there secondary branches, 

 which, in turn dividing dichotomously, give to the whole structure the 

 root-like appearance represented in the figure. The retraction of these 

 singular organs is accomplished by a sort of inversion of the above pro- 

 cess, each filament shrinking as it were into itself until it totally disap- 

 pears. The most remarkable circumstance, however, observable in the 

 economy of these creatures is, that the protruded filaments are able to 

 coalesce and, as it were, to become fused together, forming a gela- 

 tinous network that spreads out in all directions (fig. 1, 2). 



