48 THE EVOLUTION OF MAN. 



each part of the body is every other part. Each part can 

 absorb and digest nourishment ; each part is excitable and 

 sensitive ; each part can move itself independently ; and 

 lastly, each part is capable of reproduction and regenera- 

 tion. 



The reproduction of Monera always occurs asexually. 

 In the Protamoeba (Fig. 163), each individual, after it 

 has grown to a certain size, simi)ly separates into two 

 pieces. Kound the circumference of the body a contraction 

 arises, as in cell-division. The connection between the two 

 halves continually becomes more slender (B), and finally 

 parts in the middle. Thus, in the simplest possible way, 

 two new individuals proceed by self-division from one 

 quite simple individual (C). Otl.er Monera, after they have 

 grown to a certain size, gather themselves together into a 

 spherical form. The globular protoplasmic body exudes 

 a jelly-like protecting envelope, and a breaking-up of the 

 whole plasson-ball takes place within this covering ; it 

 breaks either into four pieces (Vampyrella), or into a 

 Jaige number of smaller globules {Protortionas, Protomyxa ; 

 cf Plate I. in the " Natural History of Creation "). After 

 a time, these globules begin to move, split the integument 

 by their movement, and emerge; after which they float 

 about by means of a long, thin, thread-shaped process. 

 Each again passes by simple growth into the mature form. 

 Thus, it is possible to distinguish different genera and 

 species of Monera, on one hand, by the form of the different 

 processes of the body, and, on the other hand, by the 

 difierent kind and manner of reproduction. In the appendix 

 to my monograph of the Monera I enumerated eight genera 

 and sixteen species (" Biol. Studien," vol. i. p. 182). The 



