396 7 HE BEGINNINGS OF LIFE. 



ments are seen to take place in the masses, causing 

 movements to and fro of the contained granules and 

 vesicles, and also producing extremely slight and tem- 

 porary irregularities in the outline of the sphere. We 

 have, in fact, to do with artificially separated masses 

 of the algoid protoplasm which are already more than 

 half amoeboid in nature. 



The changes that take place in an unhealthy fila- 

 ment are therefore not difficult to understand. When 

 the conditions are unfavourable for the continuance of 

 the life of the Alga, portions of its protoplasm of 

 various sizes become individualized within the fila- 

 ment ; and such a change may simultaneously affect the 

 whole of the protoplasmic contents of a certain length 

 of filament, so that on microscopical examination it 

 may be seen to have become arranged into spheroids 

 of various sizes, from ^W to -^' in diameter (a). In 

 this stage the chlorophyll vesicles within the spheres 

 may be perhaps of a brighter green than usual, whilst 

 here and there, in some of the spheres, they may have 

 begun to decolourize by assuming various tints of olive- 

 green. In this stage the individualized masses are 

 quite motionless, or at most they merely exhibit some 

 very slight alterations in the disposition of the dia- 

 phanous protoplasm existing at their surface (c). Others 

 of them, however, whilst their contained chlorophyll 

 vesicles are still unaltered, protrude a few pseudopodia, 

 by the languid contraction and extension of which the 

 masses very slowly move from place to place (). On 



