394 THE BEGINNINGS OF LIFE. 



necessarily expect to be able exactly to confirm the obser- 

 vations of others. They will soon gain an insight into 

 the rich variety of possible transformations, and will 

 recognize the difficulty of obtaining at will an exact 

 repetition of many of those which they have themselves 

 observed. 



Nothing surprised me more, on the very first occasion 

 on which I examined one of the common species of 

 Vaucheria, obtained from a road-side ditch, than to find 

 how easily many of the phenomena which have hitherto 

 been described might be observed. The marvel was 

 how so many of the naturalists who had been inves- 

 tigating these Algae could have failed to appreciate the 

 real nature of the changes which they must have seen 

 so often. We may constantly observe, within a dying 

 filament of Vaucheria, aggregations of protoplasm and 

 of chlorophyll vesicles, of various sizes, some of which 

 are quite irregular in outline whilst others are spherical 

 and with or without an enveloping membrane or cell 

 wall. ome of these masses are as much as T J</' in 

 diameter. After a time, the chlorophyll gradually 

 loses its colour, and all intermediate stages may be 

 recognized between such spherical masses and others in 

 which the central region is stained by a deep brown 

 colour, whilst the peripheral portions are more colour- 

 less and homogeneous. In this latter stage the masses 

 seem to have undergone two principal modifications. 

 A certain number of them have become encysted, 

 the cyst wall being very thick; whilst others present 



