CATAGENESIS. 219 



limbs would be of no use to them. Some of them, the 

 Angiostomata, are now subterranean in their habits, 

 and most of them are blind, or nearly so. These forms 

 present rudiments of limbs, which leads to the supposi- 

 tion that they are near to the ancestral t3^pes. From 

 such forms they developed a type which has proved 

 competent to compete successfully with other verte- 

 brates on the ground, in the water, and in the trees of 

 the forest. 



From what has gone before it is now clear that 

 while kinetogenesis is a factor in progressive evolu- 

 tion, the reverse process, or akinetogenesis, is as defi- 

 nite a factor in degeneracy. The evidence derived 

 from parasitism and sedentary modes of life is conclu- 

 sive in this direction. 



I now cite another example of catagenesis which 

 throws much light on the origin of the vegetable king- 

 dom. I have advanced the hypothesis^ that plants 

 are the degenerate descendants of protozoan animal 

 ancestors, and I will now produce some of the evi- 

 dence on which the hypothesis rests. The Myxomy- 

 cetes or Mycetozoa occupy debatable ground between 

 the vegetable and animal kingdoms. They seem at 

 one period of their history to pertain to the former and 

 at another to the latter. 



These organic beings are claimed by both botanists 

 and zoologists, the former placing them with the 

 Fungi, the latter including them in the Protozoa. 

 The fact is that in their mature form they enter the 

 Fungi, while in their early stages they are Protozoa. 

 They have distinct reproductive structures, which pro- 

 duce spores. From each spore issues a "flagellula," 

 which is a simple cell with a flagellum, not apparently 



1 Origin of the Fittest, pp. 431-432. 



