30 SYNOPTIC COLLECTION. 



The process of division is illustrated by PL 14, figs. 2-5. 

 First a swelling (fig. 2) is seen at the mouth of the shell 

 which approaches the spherical form (fig. 3). The pro- 

 toplasmic swelling reached in time the size of the parent 

 form and a mass of glass splinters was seen entering 

 the newly formed half (fig. 4) where the protoplasm with 

 the splinters showed a slowly flowing movement. In the 

 most advanced stage of division the protoplasm which 

 had curved forward had taken the form of a Difflugia 

 shell, and the glass splinters were placed in a layer upon 

 its surface (fig. 5). The new half did not seem to have 

 a firm shell, as the splinters of glass were still quite 

 loosely joined to one another. The next day the zoon 

 separated from the parent, its shell assumed the charac- 

 teristic form, while the pieces of blue glass were united 

 by means of a binding material which was still quite 

 colorless, and which, after some days, began to assume a 

 darker brownish shade. Verworn succeeded in taking off 

 the shell and obtained the naked Difnugia. Several of 

 these shell-less specimens he kept for three weeks, and 

 no attempt was made on the part of the animal to make 

 a new shell. He therefore concludes, after many experi- 

 ments, that the species of Difnugia do not reconstruct an 

 injured shell nor make another when one has been 

 removed. 



The Foraminifera are Rhizopods in which the pro- 

 toplasm is differentiated into ectosarc and endosarc, and 

 the nucleus has a membrane, a distinct chromatin net- 

 work with one or more nucleoli (Biitschli). In certain 

 forms, like Trochammina (= Rotating) inflata, and in 

 Ovulina, one half of the nucleus has been found to con- 

 sist of chromatin, the other of a non-staining substance. 

 The less differentiated Foraminifera possess a one cham- 

 bered shell, and are single forms, while the most differ- 

 entiated have a complex, many chambered shell; each 

 chamber, it may be, representing a zoon, and if so the 



1 Throughout this Guide synonyms are placed in parenthesis. 



