318 Literature 



rudimentary sporophyte generation. This view was to a great extent upheld till recent 

 years, since the presumed sporophyte was both asexual and post-sexual, but Allen ('05), 

 who studied the cytological details of the germination of the zygote, states that the first 

 division is a reduction-division, in which case the so-called 'sporophyte' is really part 

 of the gametophyte generation (vide p. 138). 



The branching of the filaments and the general cytological characters indicate that 

 Coleochxte originated from the Cheetophoracese. 



There are only about six known species of Coleoch&te and most of them have a 

 world-wide distribution in fresh water. They are all markedly dorsiventral, occurring 

 as epiphytes on the submerged parts of aquatic phanerogams. G. scutata Breb. has a 

 somewhat irregular disc when fully grown, attaining a diameter of 700 800 ^ and is 

 much the commonest of the discoidal forms. G. orbicularis Pringsh. forms almost a 

 circular disc up to 4 mm. in diameter. C. pulvinata A. Br. forms more or less hemi- 

 spherical cushions 24 (or even 8) mm. in diameter, and is enveloped in mucilage. 



The zoogonidia are generally formed in early summer and the sexual organs in the late 

 summer and autumn, but the time of their formation depends upon both the latitude and 

 the altitude. The oospore germinates in the spring, that is to say, after its winter's rest. 



Lambert ('10) has observed some curious unattached zoosporic plants of a species 

 suspected to be C. scutata. 



LITERATURE CITED 



ALLEN, C. E. ('05). Die Keimung der Zygote bei Coleochsete. Ber. Deutsch. Botan. Ges. 



xxiii, 1905. 



ARNOLDI, W. ('13) in Flora, cv, 1913. 

 ARTARI, A. ('90). Zur Entwickelungsgeschichte des Wassernetzes, Hydrodictyon utricu- 



latum Koth. Bull, de la Soc. Imp. des natur. de Moscou, 1890, no. 2. 

 ARTARI, A. ('92). Untersuchungen iiber Entwickelung und Systematik einiger Proto- 



coccoideen. Bull, de la Soc. Imp. des natur. de Moscou, 1892. 

 ASKENASY, E. ('88). Ueber die Entwicklung von Pediastrum. Ber. Deutsch. Botan. 



Ges. vi, 1888. 

 BACHMANN, H. ('05). Botanische Untersuchungen des Vierwaldstatter Sees. Ber. 



Deutsch. Botan. Ges. xxiii, 1905. 

 BERTHOLD, G. ('80). Zur Kenntnis der Siphoneen und Bangiaceen. Mitteil. der zool. 



Stat. Neapel, ii, 1880. 

 BLACKMAN, F. F. ('00). The Primitive Algse and the Flagellata : An Account of the 



Modern Work bearing on the Evolution of the Algae. Ann. Bot. xiv, 1900. 

 BLACKMAN, F. F. & TANSLEY, A. G. ('02). A Revision of the Classification of the Green 



Algaa. New Phytologist, i, 1902. 

 BOHLIN, K. ('97). Die Algen der ersten Regnell'schen Expedition. I. Protococcoideeu. 



Bih. till K. Sv. Vet.-Akad. Handl. Bd. 23, Afd. iii, no. 7, 1897. 

 BOHLIN, K. ('01). Utkast till de Grona Algernas och Arkegoniaternas Fylogeni. 



Upsala, 1901. 

 BORGE, 0. ('06). Siisswasser-Chlorophyceen vori Feuerland und Isla Desolacion. 



Botaniska Studier tillagnade F. R. Kjellman. Upsala, 1906. 

 BORGESEN, F. ('00). A Contribution to the Knowledge of the marine Alga- vegetation on 



