1002 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Identity of Podosphsera minor Howe, and MicrosphsBra fulvoMcra 

 Cooke.* — Miss M. Merry states that, in M. fulvofulcra Cooke there is clearly 

 a single ascus in each perithecium, thus placing it in the genus Podosphsera. 

 It agrees with the description of P. minor Howe, thus necessitating the 

 cancelling of Microsphsera fulvofulcra Cooke. 



New Section of Chytridium.t — Under the name CJiytridium Zygnematis, 

 Herr F. Eosen describes a new species parasitic on species of Zygnema, 

 especially Z. cruciatum. The swarmspores have a diameter of 3-4 [x, with 

 a single cilium from six to ten times the length of the body. Each spore 

 has a large eccentric oil-drop, and a less refrangible crescent-shaped body, 

 probably composed of nuclein. On coming to rest the cilium shortens aud 

 winds itself round the spore, and then disappears, while the spore clothes 

 itself with a thin and very extensible membrane. It then puts out a 

 germinating tube, with a small vesicle at its apex, from which it branches 

 into a mycelium within the host ; on this are produced the nearly globular 

 or slightly ovate zoosporangia, the formation of which is, under certain 

 conditions, preceded by that of vesicles containing a drop of oil. Each 

 sporangium is surmounted by a double crest of teeth or elevations, and 

 contains from eight to sixty zoospores. The species is characterized by its 

 great dependence on air, and has unusual capacity for resisting desiccation. 

 It appears nearly allied in some respects to G. Hydrodictyi ; in the mode of 

 escape of the zoospores it resembles G. MagtigotricMs. 



Herr Eosen proposes the establishment from this species of a new 

 section of Ghytridium, which he names Dentigera, with the following 

 characters : — Unicellular Ghytridia with a bladder in the cell of the nutrient 

 alga, from which proceeds a branched mycelium, and a more or less nearly 

 spherical zoosporangium, at the apex of which are (four) two-cleft teeth. 

 1 he zoosporangium is either sessile on the portion contained in the nutrient 

 cell, or one or two sometimes stalk-like vesicles are interposed. The 

 swarm-spores are globular with an eccentric oil-drop and a single cilium. 

 Eesting-spores unknown. 



To this section belong, in addition to Ghytridium Zygnematis, G. dentaium 

 n. sp., parasitic on Spirogyra orthospira, and G. quadricorne dBy., parasitic 

 on CEdogonium rivulare. 



Cladochytriuml — Nowakowski included under this genus some forms 

 of Chytridiacese with terminal or intercalary zoosporangia borne on branches 

 of a mycelium partially or entirely projecting above the surface of the 

 host ; the zoospores producing again a similar mycelium without conjugat- 

 ing. Other forms producing resting- spores were believed by de Bary to be 

 stages of development of the same fungus ; and this has now been confirmed 

 by Dr. M. Biisgen, who has followed out the whole cycle in Cladochytrium 

 Butomi, parasitic on the stem and leaves of Butomus umbellatus. The 

 development is characterized by the formation within the host-cell of 

 swellings, within which are stored substances which are subsequently used 

 up in the production of hyphse and of resting-spores. In the same nutrient 

 cell will sometimes be produced two kinds of swarmspore : one penetrates 

 into the host and produces plants which bear resting-spores ; the other kind 

 is transformed almost directly into a second generation of zoosporangia. 



In Gladochytrium Flammulse, parasitic on Banunculus Flammula, and 

 G. Menyanthis on Menyanthes trifoliata, Dr. Biisgen has been able at present 

 to detect the formation of resting-spores only. 



* Bot. Gazette, xii. (1887) pp. 189-91 (1 pi.). 



t Cohn's Beitr. z. Biol. d. Pflanzen, iv. (1887) pp. 253-67 (2 pis.). 



X Ibid., pp. 270-83 (1 pi.). 



