GENERAL SKETCH 



59 



or gemmation which is common among the Suctoria and some of the 

 Flagellidia, less frequently observed in the Ciliata, and is possibly 

 allied to " spontaneous division " among Sporozoa. 1 A piece of the 

 nucleus of the mother-animal is pinched off and becomes the nucleus 

 of a much smaller daughter-cell, which usually arises from a certain 

 definite place on the parent (Fig. 28). When numerous pieces are 

 thus budded off, and each piece is surrounded by a bit of protoplasm, 

 the process is again akin to spore-formation (Noctiluca). 



Spore-formation may thus be accomplished either by the repeated 



I"..* -A B c 



Fig. 29. Onychodromus grandis Stein. [MAUPAS.] 

 A. Normal individual. B. Smaller form without micronuclei ; degenerate. C. A still more 

 reduced and degenerate form. N, macronucleus ; 'n, micronucleus. 



division of the entire animal, repeated division of the nucleus, the 

 products of which are later surrounded by minute bits of cytoplasm, 

 or by fragmentation of the nucleus without the formality of regular 

 division. In the latter case the body of the animal breaks up simul- 

 taneously into many hundreds of small pieces, each surrounding one 

 of the nuclear fragments and developing later into the parent form 

 (faramceba). 



So-called sexual reproduction or some modification of this process 

 is accomplished, either directly or indirectly, by the temporary or 

 permanent union of two individuals of the same or of dissimilar size. 



1 See Chapter IV, p. 159. 



