THE NEW GENEALOGICAL TREE 363 



All these suggestions have a strongly hypothetical cha- 

 racter. It is therefore not surprising if we find numerous other 

 interpretations of this development. A majority of zoologists 

 consider that the Ciliata represent a blind side branch of the 

 Protozoa, and that the Metazoa had evolved directly from the 

 colonies or aggregations of the genuine Flagellata. It is believed 

 that this latter evolution had been either monophyletic (e.g. 

 from the Choanoflagellata, according to Lameere) or diphyletic 

 (once as Spongiae and the second time as Eumetazoa). We will 

 not mention here all the other interpretations which are even 

 less probable or which are occasionally quite bizarre. We can 

 give here as an example only the interpretation that was 

 proposed by Awerinzew (1910); he considers that the Metazoa 

 did not evolve from the Protozoa, and that instead the two 

 groups developed simultaneously along two parallel lines of 

 evolution from some even more primitive ancestors. Franz, 

 too, considers that the Protozoa and the Metazoa only had 

 some common ancestors; these ancestors were algae which 

 had already reached a somewhat higher level of development 

 and which afterwards evolved on the one hand into the Proto- 

 phyta and these into the Protozoa; the higher plants had 

 evolved from the Protophyta parallel to the development of 

 the Protozoa; the other Hne of evolution had gone from the 

 algae by way of a "blastaea" tow^ards the Metazoa. Fortunately 

 enough, such extravagant interpretations have never been 

 accepted by anybody. 



It is generally considered that the Ciliata evolved (mono- or 

 polyphyletically?) from the Zooflagellata; yet no recent 

 transitional forms have ever been found, neither do w^e know 

 of any transitional forms between the Ciliata and the Metazoa. 

 Zoologists have tried to avoid these difficulties by referring 

 to the pattern that can be observed in plants, yet at the same 

 time they have completely forgotten that this is a pattern only, 

 an analogy, which represents a possibility and which must not 

 be interpreted as an indication and even less so as an evidence. 

 There are a few facts only which take place in the ontogenies 



