504 SUMMARY OF CURRENT RESEARCHES RELATING TO 



contents are green and granular, witli a few starch-grains. The in- 

 crease takes place in two ways : by vegetative division of the cells of 

 which the colony is composed ; and by zoospores distinguished into 

 microzoospores and niegazoosjjores. These are formed respectively 

 eight and four in the mother-cell, and escape by a horizontal slit in 

 the cell-wall. No difterence in function was detected between the two 

 kinds of zoospore, both germinating after coming to rest. The fol- 

 lowing is the diagnosis of the species and genus, its nearest allies 

 being Cosmocladium and Mischococcus : — 



Hauchia n. gen. Cellulte ovales v. ellipticae, geminae, stipite 

 longo hyalino recto aut leviter incurvo instructas, altera apicalis, altera 

 latere interno media parte stipitis inserta ; divisio cellnlarum ad tres 

 directiones alternans ; stipitis quasi ramuli repetite bifurcato-articu- 

 lati, et cellulas in colonias eleganter cesjiitosas componentes, sed «tate 

 provecta soluti. Propagatio e zoosporis (macro- et micro-zoosporis) 

 usque ad octo in cellulas matricales ortis, et pariete transverse 

 circumscissa, libere erumpentibus : propagatio sexualis adhuc ignota. 



H. insularis aj). noy. Diam. cell. 0" 004-0 '007 mm.; long. stip. 

 0' 15-0 "32. Habitat ad rupes calcareas madidas insulae Aegusas 

 (Favignana). Leg. Feb. 1879. 



Formation of the Sporangia in Halimeda.* — F. Schmitz de- 

 scribes the formation of the sporangia and zoospores in Halimeda 

 Tuna, macroloba, and platydisca. The fructiticati> in of the first of 

 these species was described by Bompard as a parasitic organism 

 under the name Botryophora dichotoma. According to Schmitz, the 

 branches of the thallus bear on their upper margin dark green tufts of 

 fructification, composed of simple or forked hyphae on which the 

 sporangia are clustered, their entire space being filled with protoplasm. 

 This protojilasm breaks up into a number of small zoospores, which 

 escape from the sporangium through an irregular slit, and come to 

 rest after a period of active motion. Their further development was 

 not observed. 



According to Zanardini, the fructification of H. macroloba is quite 

 similar, while that of H. platydisca Dene, presents some differences. 

 This species, although hitherto known only from the Canary Isles, is 

 widely distributed through the Mediterranean, and may be readily 

 confounded with H. Tana, from which it is distinguished by the 

 larger size of the thallus. and chiefly by its fructification. The 

 sporangia are here the swollen apices of short dichotomously branched 

 hyphae, which spring densely crowded from the entire margin, and 

 also sparsely from the surface of the branches of the thallus. The 

 escape of the zoospores was observed also in this species, but not their 

 further development, nor any conjugation. 



Spirogyras of the Environs of Paris.! — ?• Petit enumerates and 

 describes thirty-sis species of Spirogyra from the neighbourhood of 



* SB. niederrhein. Ges. Natur. u. Heilkunde, Bonn, ] 880. See Bot. Centralbl., 

 i. (1880) p. 1282. 



+ Petit, P.. ' Spirogyra des environs de Paris ' (12 pis.), Paris, 1880. See Bot. 

 Centralbl., i. (1880) p. ICOl. 



