402 THE BEGINNINGS OF LIFE. 



globular Monads. Other decolourized vesicles^ instead 

 of developing a blind tube, protrude a hemispherical 

 outgrowth, from which beautiful tree-like ramifications 

 of delicate branches extend [d). These three forms seem 

 to be most intimately allied to one another — ^judging 

 from the ease with which apparently similar vesicles 

 may take on now one now another of such modes of 

 transformation. 



3. Or if the temperature happens to be not lower 

 than do^F, the whole substance of the embryonal 

 spheroid may at once segment into small and very 

 active non-nucleated Monads {c'). This segmentation 

 begins at the periphery in the colourless portions of 

 the spheroid, whilst subsequently the more central parts 

 gradually undergo a similarly complete decolourization, 

 and segmentation of them also goes on. Sometimes the 

 most superficial layer is involved in the transformation, 

 so as to leave no bounding membrane, and then in the 

 course of an hour or so, when the Monads begin to 

 exhibit movements (owing to the development of the 

 flagellum), they may swim away one by one. But at 

 other times a very thin, cyst-like, outer layer is left, so 

 that after the whole of the contents has been trans- 

 formed into Monads, they may be seen in pretty active 

 movement before they succeed in rupturing their deli- 

 cate enveloping membrane. In some instances (c) a mass 

 of blackish brown granular matter remains as a refuse 

 product (especially in cases where the change has not 

 gone on very actively), though in other spheroids the 

 whole of the matter undergoes conversion. 



