1038 SUMMARY OF CURRENT RESEARCHES RELATING TO 



in the genera Hajpalosiphon, Mastigocladus, Sirosiphon, Stigonema, 

 Fischera, and Fhragmonema, placed under Sirosiplionacese. 



7. Some CMorophycacese are, like most ScLizophyccse, also poly- 

 morphic algae. Most of the filamentous chlorophyll-green algae 

 which are placed in the genera Gloeotila, Mia-ospora, Conferva, 

 Psichohormium, Mliizoclonium, Hormiseia, TJlcthrix, Hormidium, Schi- 

 zomeris, and Schizogonium, are connected genetically with other more 

 highly developed eilgss belonging to the familieo OhsetophoraceEe, 

 Sij)honocladace£e, and Ulvaceae. By the swelling and separation of 

 the cell-walls, and by continuous division, there arise from the last- 

 named and other families of the higher algae, various unicellular algae 

 in the broader sense of the term, which are placed under the genera 

 Protococcus, Palmella, Pleurococcus, Chlorococcus, Gloeocystis, Inoderma, 

 SticJiococcus, Dactylothece, Palmogloea, ScMzochlamys, Oocystis, Nephro- 

 cytium, Palmodactylon, Dictyosphserium, Gemmella, Hormosjpora, Apio- 

 cystis, AcantTiococcus, Polyedrium, Characium, and Hydrianum. 



The author describes the mode in which the various forms of algae 

 here named may develope one out of another ; and regards also the 

 Schizophyceae and Schizomycetes as connected with one another by 

 insensible gradations. Thus we may have one and the same alga 

 occurring in its fully developed form, and in its Stigonema, Lynghya, 

 unicellular, Nostoc, XJlothrix, and a variety of other forms. Of this a 

 number of examples are given. 



The various species of Euglena, hitherto included under Flagellata, 

 especially E. viridis, have been discovered by Dr. Hansgirg to be 

 genetically connected with the PhycochromaccEe or OscillariaccEe. 



Finally, a further analogy between the Schizomycetes and Schizo- 

 phyceae is established by the discovery in the latter of a hitherto 

 unobserved swarming condition. This condition would appear to be 

 extremely rare ; but under the name Chroomonas Nordstedtii, Dr. Hans- 

 girg describes a unicellular biciliated organism with blue-green 

 endochrome, which he regards as the swarm-cell condition of a 

 phycochromaceous alga which occurs normally in the filamentous 

 form, probably Oscillaria tenuis or Frblichii. 



Chlorophyll-green of Fucacese.* — Dr. A. Hansen details the 

 method by which he extracts pure chlorophyll from Fucus vesiculosus, 

 and describes the peculiarities of its spectrum, showing that it differs 

 in no essential point from that of the higher plants. The spectrum 

 of living Fucus shows four absorption-bands of the chlorophyll, one of 

 the brown pigment, while the bands of the chlorophyll-yellow are 

 not seen, being concealed by the strong absorption in the blue. 



Bisexuality of the Zygnemacese.f — Prof. C. E. Bessey considers 

 that these organisms do not possess true bisexuality. All the ob- 

 served facts of the conjugation of these algae tend to prove that 

 sexuality is in its beginning, but as yet there is no differentiation 

 into male and female elements ; so that we cannot speak of a bisexuality, 



* Arbeit. Bot. Inst. Wurzburg, iii. (1885) pp. 289-304 (1 pi.). 

 t Science, vi. (1885) pp. 224-5. (Proc. Sect, of Biology, Amer. Assoc. Adv. 

 Sci.) 



