THALLOPHYTES 



SI 



that the forms with one, two, or four eggs have been derived from those 

 with eight, some of the eggs not developing, but all eight represented 

 by nuclei. Both sperms and eggs are discharged and escape from the 

 conceptacle. Fucus is remarkable, therefore, not only in the produc- 

 tion of eight eggs by the oogonium, but also in the fact that they are 

 discharged before fertilization. The eggs float and are surrounded by 



Figs, 132-136. — Fucus: 132, young oogonia among the paraphyses; 133, an older 

 oogonium; 134, oogonium beginning to develop the eight eggs; 135, the eggs rounded 

 off; 136, the eggs escaping from the oogonium. — After Thuret. 



swarms of sperms, which have been observed to set them rotating (figs. 

 137, 138). The functioning sperm enters the egg, comes in contact with 

 its nucleus, and the two nuclei lying in contact gradually fuse. Ap- 

 parently the oospore is not a resting cell, but develops a new plant at 

 once (figs. 139, 140). 



In following the life history of Fucus it has been found that the number 

 of chromosomes, which is doubled by the fusion of the male and female 

 nuclei, is not reduced until the gametes appear. Therefore, using the 

 number of chromosomes as a test, the whole- vegetative plant is the 



