THE FORAMINIFERA 



79 



ORDER Gromiidea. 



In Euglypha (Fig. 3) multiplication, by division into two, 

 occurs as follows. 1 The specimen which is about to divide 

 secretes fresh shell plates, which are at first dispersed in the 

 protoplasm about the nucleus. The pseudopodia are with- 

 drawn, and the protoplasm is extruded beyond the mouth of the 

 test in a rounded mass. This grows until it assumes a size 

 equal to that of the test from which it protrudes, and the 

 newly-formed plates are disposed on the surface to form a new 

 test. The nucleus divides by karyokinesis, half going to each 

 end of the mass, and division of the protoplasm follows, one part 

 remaining in the old shell and the other in the new one. 



Fro. 14. 



Colony of Mikrogromia socialis in the diffused condition, a, an individual in process of 

 multiplication by transverse fission, c.v, contractile vacuole. Two of the members of the 

 colony are seen to be undergoing the same process. 



Blochmann (2) has described a process in which, after the 

 division of the nucleus, the protoplasm was withdrawn from the 

 newly formed shell, and this, together with the daughter nucleus 

 remaining in it, was cast off. It is suggested that this may be 

 comparable with the extrusion of parts of the nucleus observed in 

 some other Protozoa and in polar-body formation. But in view 

 of the fact that the new shell was cast off, as well as the daughter 

 nucleus, this interpretation appears, to say the least, forced. 



A temporary fusion of the protoplasm of two or more indi- 

 viduals, apparently without fusion of nuclei (plastogamy), was 

 observed by Blochmann, and in one instance a new individual was 

 apparently formed by the conjugation of two. In this case it 



1 The process was first described by Gruber (16), and followed out in detail by 

 Schewiakoff (48). 



