PROTOZOA. 



13 



PROTOZOA. 



Section i (horizontal part). 

 SARCODINA. MONERA. 



Scepticism prevails in regard to the existence of Hae- 

 ckel's Monera. Nevertheless, as Calkins 1 remarks, the 

 claim of Haeckel "that there are organisms without 

 nuclei .... although it rests upon negative evidence, can- 

 not be rejected until all the forms considered have been 

 shown to possess them." 



It is readily conceivable that non-nucleated forms were 

 the first to exist in a remote past, and that these antedated 

 the nucleated forms seem a reasonable supposition. Some 

 of these non-nucleated organisms have persisted, it would 

 seem, since ancient times, although it is probable that all 

 modern Protozoa differ in some respects from their primi- 

 tive ancestors. Since these earliest ancestors were made 

 of protoplasm only, being wholly without hard parts, no 

 record of their structure has been preserved in the rocks. 

 For this reason we must begin with the simplest Protozoa 

 living to-day. 



In PL i, figs. i-6a, is represented the salt and fresh 

 water form, Protamoeba primitiva Hkl., and in PI. 2, figs. 

 i-4a, a species of marine Protamoeba (P. schultzeana 

 Hkl.). There are many and strong reasons for maintain- 

 ing that the first animal life which existed was marine. 

 The first Protamoeba described and figured by Haeckel 

 (PL i, figs. i-6a) was found in fresh water, but since 

 then Protamoeba primitiva Hkl., has been discovered in 

 salt water. With our present knowledge of the properties 



1 The Protozoa, 1901, p. 40. (Columbia University Biological 

 Series, VI.) 



