INVEUTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 939 



The parasite makes its appearance in tbe form of greenish or 

 bright orange patches on the upper surface of the leaf. On detaching 

 one of these pustules from the leaf, and examining it under high 

 powers, it is found to consist of a flattened, subei^idermal disk of 

 radiating filaments, from which numerous ascending twigs arise, and 

 these, breaking through the epidermis, develop into the fructifying 

 filaments. The disk consists of a single layer of dichotomous fila- 

 ments, and increases continually at the margin. The terminal cell of 

 a fructifying filament eventually swells up into an oval, spore-like 

 body ; in this is ultimately formed a roundish orifice, from which 

 escape a number of reddish orange (by transmitted light) biciliated 

 zoospores. The sexual reproduction is effected by the fecundation of 

 oogonia by pollinodia. The resulting oospores retain their vitality 

 for a considerable time. Ultimately the contents break up into a 

 number of biciliated zoospores, precisely resembling those produced 

 non-sexually. They rupture the thin wall of the oospore, and swira 

 freely in the subepidermal space and over the surface of tlie leaf. 



With regard to the systematic position of Mi/coidea, Dr. Cunning- 

 ham considers that, notwithstanding the difterence in the mode of 

 reproduction, its vegetative structure indicates a near afiinity with 

 Coleochcete. An interesting circumstance connected with this alga is 

 that a number of the primary disks do not give rise to fructifying fila- 

 ments, but are utilized by fungal filaments, and, in connection with them, 

 contribute to the development of patches of a heteromerous lichen. 



Two new Parasitic Algse.* — An addition is made to the small 

 number of known parasitic Algas in the description by J. Eeinke of 

 two species. 



The first, a species of Anabcena, was discovered by him several 

 years ago in the roots of Cycade^e, where it forms bright gi-ecn 

 streaks visible to the naked eye. It develops in the intercelhdar 

 spaces, but has no obvious injurious effect on the host. Micro- 

 scopic examination shows it to consist of strings of globular cells 

 embedded in jelly, presenting a close resemblance to Nostoc. It has 

 been observed in the roots of Ceratozamia, Cjcas, Bioon, and Encejjlie- 

 lartos. 



The second species, to which he gives the name Entocladia viridis, 

 is parasitic on the long unicellular filaments of Derhesia Lamourouxii, 

 growing, however, not within the cell, but in the cell-wall. It is a 

 branched, multicellular, filamentous alga, nearly allied to Stigeodonium 

 and Chlorotylium. Although no reproduction of the alga has been 

 observed, this no doubt takes place by means of zoospores. 



Method of Cultivating Volvox globatoi-.f — This Alga is, accord- 

 ing to the experience of many, a most difficult one to keep for any 

 length of time, but Mr. N. E. Brown, of Kew, announces that he has 

 discovered the way to do so. 



For several years his practice was to place the Volvox in large 

 glass or earthenware jars, small bottles, open dishes, and other 

 vessels, exposed to full sun, or kept in partial or entire shade, 

 * *Bot. Zeit ,' xxxvii. (1879) p. 473. 

 t 'Gardtners' Chronicle,' 1879 (Nov. 8) p. 599. 



