216 SUMMARY OF CUKKENT KESEA.RCHES RELATING TO 



additions have been made. The present author has, however, had 

 access to samples of marine, freshwater, snb-fossil, and recent species, 

 and has added largely to the number recorded. She establishes a new 

 ecological group of diatoms — i.e. a marine-arctic formation. Many 

 new species are described and figured. 



Algae of the Missouri Botanical Garden.* — A. Hayden describes 

 the algal flora of the Missouri Botanical Garden, enumerating the 

 species of algse, and describing and figuring the different localities. 

 Observations are given on the follow ing species : — Botrydium granu- 

 latum, Spirogyra longata, S. porticalis, S. ienuissvma, Ghlamydomonas 

 gheocystifornm, Tetraedron trigonum, Stigeodonium glomeratum, and 

 Pithophora Mooreana. 



Cladophora in Deep Water.t— E. M. Kindle gives an account of a 

 Clndophora found growing on curiously corroded limestone (" honey- 

 comb rock ") at the remarkable depth of 150 feet in Lake Ontario. 

 Upon investigation the alga was determined as Cladophora profunda 

 Brand, which occurs in the lakes of the Bavarian Alps, at depths not 

 exceeding 50 feet. The plant is a new record for America, and is 

 distinguished q& forma ima from the European type. 



Mougeotia.J — R. Chodat publishes the second of his studies on the 

 Coujugatie. The subject is the copulation of Mougeotia. He begins 

 by quoting the general view as expressed by Oltmanns, that Sirogonium, 

 Mougeotia, and other algae, produce knee-like out-growths which form 

 contact with one another and coalesce. This view is shown to be 

 incorrect. Contact is necessary for the production of copulative 

 anastomoses, and as copulation advances, so the knee-like outgrowths 

 increase in size. As many as three filaments connected by anastomosis 

 have been observed. The formation of an azygospore is also described 

 and figiu'ed. Its production might be attributed to a general influence, 

 bringing into play the formation of copulative branches, which, failing 

 a vis-a-vis, were transformed into a zygote. But if the course of the 

 azygospore filament be followed it is seen that copulation has taken 

 place on that filament ; and the formation of the azygospore is probably 

 the result of the impetus there given. The result of the investigation 

 shows that the exciting cause of the copulative anastomoses is contact, 

 haptotropism. Nevertheless it is evident that sensibility to contact is 

 not constant, since the filaments are continually in contact without the 

 production of a zygote. The sensibility is an affair of maturation. 

 The necessary condition must be present, and the key to that is at 

 present unknown. 



Development of Saccorhiza bulbosa. — C. Sauvageau describes the 

 germination of Saccorhiza balhosa, and the first stages of the developing 

 plantlet. After swimming about for some time, the zoospore comes 



* Twenty-first Ann. Rep. Missouri Bot. Garden, 1910, pp. 25-48 (5 pis.). 



t Amer. Journ. Sci., xxxix. (1915) pp. 651-6 (figs. J 



X Bull. Soc. Bot. Geneve, s^r. 2, v. (1913) pp. 193-5 (figs.). 



§ Comptes Eendus, clxi. (1915) pp. 740-2. 



