SUMMARY OF ALG^E. 135 



parent into bodies capable of germination, such portions 

 being in most instances capable of performing spontaneous 

 movements by means of cilia. Advancing one step further, 

 we find the sexual mode of reproduction indicated by the 

 conjugation or blending together of two such ciliated 

 bodies — zoogametes — to form a body capable of developing 

 into a new individual. A modification of the above mode 

 of conjugation between two motile cells is presented by 

 Spirogyra, where the naked masses of protoplasm do not 

 leave the parent cell before conjugating, and the amount 

 of movement for effecting this object, although less evident 

 than in the preceding examples, is still necessary. It will 

 be noticed that amongst the most primitive groups of plants 

 produced sexually, the two elements are as a rule formed 

 by distinct individuals ; in other words, cross-fertilization is 

 in many instances secured. By degrees the distinction 

 between the male and female elements of reproduction 

 become sharply defined, and the female body or oosphere 

 becomes immotile, and remains so throughout the Vegetable 

 Kingdom. Notwithstanding the amount of progress made 

 by the sexual mode of reproduction in the AlgEe, on the 

 whole the asexual mode is most frequent throughout the 

 entire class. 



True alternation of generations does not occur in the 

 Algae. What has been considered aS such by some author- 

 ities, is thus stated by Bennett and Murray.^ " A very 

 singular genetic connection exists between the genera 

 Chantransia and Batrachospermum, it being possible to 

 transform the former into the latter by changing its con- 

 ditions of life. The germinating carpospores of Batracho- 

 spermum put out a kind of protoneme, which is the 

 ' Crypt. Botany, p. 214. 



