8o 



THE FORAMINIFERA 



\ 



was supposed that the nuclei had united (karyogamy) as the new 

 individual was uninucleate. 



Encystment also occurs in Euglypha, but what the subsequent 

 stage may be is unknown. 



Mikrogromia socialis, first described by Archer, 1 and afterwards 

 more fully by R. Hertwig (18), is a fresh-water form, occurring in 

 colonies, the members of which are united by their pseudopodia. 

 The colonies are sometimes globular and compact (Cystophrys 

 stage), sometimes diffused (Fig. 14), and in the latter condition 

 present an interesting resemblance to a brood of young megalo- 

 spheric individuals of Polystomella in a stage of dispersal 

 (Fig. 10, d). 



The growth of the colony results from the partial longi- 

 tudinal fission of the members into two (or three), one (or two) of 



the products of fission escaping, 

 secreting a new test, and taking its 

 place in the colony. Hertwig also 

 observed the production of young 

 individuals, arising by transverse 

 fission (Fig. 14, a). Of the two bodies 

 so formed one remains in the test, 

 continuing the vegetative phase of 

 the parent, the other becomes free, 

 and, in some cases, swims away as 

 a biflagellate organism. In other 

 cases, however, the flagella were not 

 observed, being replaced by pseudo- 

 podia, resembling those of Actino- 

 phrys. The further history of the 

 young thus produced was not 

 followed. Assuming this to be a 

 normal phase of development of 

 Mikrogromia, it appears to be with- 

 out a parallel in the life-history of 

 Polystomella. 



Hyalopus dujardinii, Schaudinn 

 ( = Gromia dujardinii, M. Schultze) is 

 a marine form distinguished by the 

 hyaline and nongranular character of 

 its pseudopodia, and by the absence 

 of anastomoses between their branches. 

 The main body of the protoplasm is 

 covered by a chitinous envelope, and contains large brown 

 rounded granules and many nuclei. In the condition in which it 



FIG. 15. 



Hyalopus (Gromia) dujardinii. 

 (After M. Schultze.) 



X 40. 



1 Provisionally as two species, Cystophrys haeckeliana and Gromia socialis 

 Archer (1). 



