18 SYNOPTIC COLLECTION. 



An unfilled gap exists between these forms, which are 

 among the more undifferentiated members of the Monera 

 and the Protomyxa, which Haeckel considers a Moner 

 and Biitschli a Rhizopod. No nucleus has been dis- 

 covered in Protomyxa, and for this reason we do not feel 

 justified in placing it with the Rhizopods. On the other 

 hand, the habit of fusing or blending with other zoons 

 of its own kind, of covering itself with a hardened case or 

 cyst and passing into a resting state, and especially of 

 producing flagellate young, makes it seem not improbable 

 that flagellate unnucleated adults which have arisen 

 through adaptation of structure to habit may have existed 

 as the ancestors of Protomyxa. This may be the case or 

 else a nucleus may be found, when the Protomyxa can be 

 placed among the Rhizopods as Biitschli has already done. 



The experiments of Gruber on Dimorpha mutans (PL 

 50, figs. 1-9) suggest still another view, namely, that the 

 flagellate condition may be assumed quickly in response 

 to the need for rapid motion. Therefore, the flagellum 

 in many cases of these simpler Protozoans may often be 

 an adaptive and not an inherited character. 



PI. 7, fig. i, represents the younger stage of Protomyxa 

 as it issues from the cyst. After the exit it adopts the 

 more usual crawling motion, thereby assuming the Pro- 

 tamoeba-like form (PI. 7, fig. 2) and showing an interme- 

 diate stage between the flagellate and the Protamoeboid 

 condition. In PI. 7, figs. 3, 4, the Protamoeboid state is 

 more pronounced. PI. 7, fig. 5, is a single zoon showing 

 the function of nutrition, a Navicula being assimilated by 

 the plasma of the body. After nourishment is taken, 

 vacuoles or cavities filled with fluid and without distinct 

 walls begin to appear which are not found in the young 

 (PI. 7, figs. 1-3). A form like PL 7, fig. 5, was seen to 

 fuse with a similar zoon. PL 7, fig. 6, represents three 

 or four zoons that have fused together. PL 7, fig. 7, is 

 an adult formed by the fusion of several zoons, and PL 7, 

 fig. 8, an adult after- being well fed. The vacuoles are 



