VEGETATIVE PROPAGATION 331 



was then frozen; and these were found to germinate readily when 

 afterwards exposed to suitable conditions. The other half were 

 not subjected to the action of frost; and these could not be made 

 to germinate, even though the water had been cooled to a point 

 slightly above the freezing-point. It thus appears that the buoy- 

 ancy, so far from being a risk, is a means of exposing the stato- 



Fig. 857. Winter-Buds of Moss-Polypes, enlarged to various scales 



A, Small part of colony of Paludicella, with individuals expanded. B, Remains of part of colony of same, 

 attached to stone and showing external winter-buds (w.l>.}. c, Simple statoblast of Fredericella. D, E, F, 

 Floating statoblasts of Plumatella, Lophopus, and Cristatella. 



blast to the conditions which are most favourable to its later 

 development." 



Moss- Polypes easily replace lost parts, and in most cases a 

 large part of the body degenerates at regular intervals, and is as 

 constantly re-grown from the part which remains. It has been 

 suggested that this may be a radical sort of way of getting rid 

 of waste products. 



Vegetative Propagation and Regeneration in the Higher Groups 

 of Many -celled Animals (Metazoa). With increasing complexity 

 of structure the possibilities in these directions become more and 

 more limited. In Molluscs (Mollusca) and Jointed-limbed Inverte- 

 brates (Arthropoda) multiplication by means of budding or fission 

 is no longer possible, though there is often considerable power of 

 re-developing parts of the body which have been lost. The limbs 



