tto.525] SEXUAL REPRODUCTION IN ALGJE 



517 



the second division, a phenomenon very characteristic 

 of the reduction divisions of higher plants. The degen- 

 eration of three of the four nuclei which result from the 

 two mitoses within the zygospore of Spin>f/i/r<i is of 

 course an illustration of that conservation of material for 

 a single reproductive cell which finds its analogy in the 

 history of development of certain megaspores at the ex- 

 pense of their neighbors and in the maturation of the 

 animal egg. 



It seems probable that studies upon the germinating 

 zygospores and oospores of other green algje will estab- 

 lish them to be the seat of reduction phenomena similar 

 to that described above, although such investigations are 

 beset with many technical difficulties. It is to be hoped 

 that we may soon have information on these conditions 



of auxospores among 1 the diatoms take on new interest 

 in relation to the conditions in Spiror/i/ra. In none of 

 these forms have we at present any reason to expect the 



iar interest chiefly perhaps because its oospore on ger- 

 mination gives rise to a small group of cells, each of 

 which develops a zoospore. It is not strange that this 

 cellular structure, a phase intercalated between two sex- 

 ual plants, should have been compared with the simplest 

 types of sporophytes in the liverworts, and that in at- 

 tempts to bridge the gap between the thallophytes and 

 bryophytes Coleochate should have been brought for- 



