1912 BARRETT— BLASTOCLADIA 369 



6. On germination the zoospore produces a germ tube which 

 forms the basis of the rhizoid system, while the body of the spore 

 becomes the basal cell of the plant. 



7. Nuclear division is somewhat unusual, apparently, and 

 reminds one of amitosis. It seems to the writer, however, that it 

 is more probably a form of mitotic division dealing with a single 

 large chromosome. 



LITERATURE CITED 



Rabenhorst 



1892. 



Harper 



Ann. Botany 13:467- 



525. pis. 24-26. 1899. 

 3. Humphrey, J. E., The Saprolegniaceae of the United States, with notes on 

 other species. Trans. Am. Phil. Soc. 173:63-148. pis. 14-20. 1893. 



4- Petersen, H. E., Studier over ferskvands-phykomyceter. Saertryk af 

 Bot. Tidssk. 29:345-440. figs. 27. 1909. 



5- Pringsheim, N., Ueber Cellulinkorner, eine Modifikation der cellulosen 

 Kornerform. Ber. Deutsch. Bot. Gesells. 1:288-308. pi. 7. 1883. 



o. Reinsch, P. F., Beobachtungen iiber einige neue Saprolegnieae, etc. 



Jahrb. Wiss 



Thaxter 



J., Engler und Prantl 



2. Gonapodya Fischer and 



Myrioblepharis, nov. gen. Bot. Gaz. 20:477-485. pi. 31. 1895. 

 9* , New or peculiar aquatic fungi. 3. Blastocladia. Bot. Gaz. 



21 : 45-52. pi. 3. 1896. 



I0 * ' , New or peculiar aquatic fungi. 4. Rhipidium, Saprotnyces, and 



Araiospora, nov. gen. Bot. Gaz. 21:317-331. pis. 21-23. 1896. 



EXPLANATION OF PLATES XVIII-XX 



Fig. i. — Biciliated zoospore. 



Fig. 2. — Different stages in the germination of the zoospore. 

 ( Fig. 3. — Young plant with basal cell showing rhizoids and two branches 

 which are beginning to branch dichotomously. 



Fig. 4.— Young plant started on potato agar and subsequently transferred 

 to water where sporangial development took place. 



Fig. 5.— Plant similar to the one shown in fig. 4, with an empty sporangium 

 and another almost mature below it. 



Fig. 6.— A branch with sympodial arrangement of resting sporangia. 



Fig. 7.— Resting sporangia more closely arranged on the branchlet, a more 

 frequent condition in old cultures. 





