448 SUMMARY OF CURRENT RESEARCHES RELATING TO 



belonging to the genera Nuclearia, Heterophrys, and Actinophrys. Next 

 come tlie zoosporous Monadine^, of which the genera Pseudospora, Barbetia 

 n. gen. (Pseiidospora Volvocis Cnk.) and Soretia are treated. In this family 

 should be placed Chytridium destruens Now. 



The family most nearly allied to the Vampyrelleae of an undoubtedly 

 vef^etable character are the Chytridinese. Their close alliance to the 

 Flagellata is confirmed by the discovery of a new genus of Chytridineae 

 carrying on a parasitic life within Euglena viridis and other Flagellata and 

 Ehizopods, to which M. Dangeard gives the name Spliserita. It occurs in 

 the form of large spherical masses which break uj) into zoospores which 

 escape by the rupture of the wall of the host ; each zoospore has a long 

 strongly curved cilium placed in front. The author gives a series of reasons 

 for concluding that these organisms cannot be endogenous reproductive 

 germs of the host. Cysts are formed, but only very rarely. The nearest rela- 

 tionship of Sphserita endogena is with Minuhilaria [Chytridium) destruens, from 

 which it differs in scarcely any other point but in its mode of nutrition. 



Sjjhserita the author regards as the lowest member of the Chytridineae ; 

 next to it come Olpidium and OlpAdiopsis. Olpidium apiculatum Br. is the 

 early stage of a Bhizidium ; 0. zootocum Br. is identical with Catenaria 

 AnguilMse Sorok., and should be placed among the AncylisteEe. Then 

 follow descriptions of the genera Chytridium and Bhizidium, with some of 

 their sj^ecies. 



The Ancylistese are allied to the Chytridineae through Catenaria ; while 

 Ancylistes leads, on the other hand, to the Peronospore^ ; Pythium dicho- 

 tomum sp. n. appears to be a sexual phase of Catenaria. The cycle of 

 development of Ancylistes is completed by the germination of the oospores. 



Structure of Nostochinese.* — In a general review of the structure of 

 the Nostochinefe (Nostocaceae, Eivulariaceae, Oscillariaceae, Scytonemaceae, 

 and Stigonemaceae), Sig. A. Borzi states that the gelatinous sheath which 

 invests each filament is reduced to very small dimensions in Oscillaria, and 

 is entirely wanting in Borzia. The number of cells of which the hormo- 

 gones consist is very variable, and may be reduced to two ; in a few species 

 only is it constant, viz. three in Borzia trilocularis, four in Dactyloglcea 

 prasina sp. n., eight or sixteen in Seguenzsea, an undescribed genus of Stigo- 

 nemacete. The hormogones are either perfectly straight or spiral, the former 

 moving in a straight line, the latter describing with their apices a helicoid 

 curve. This difference is accompanied by special biological peculiarities. 



The straight homogones are always entirely destitute of any gelatinous 

 sheath, as in Lynghya, Plectonema, the Nostocacete, Scytonemaceae, Rivu- 

 lariaceae, and Stigonemacese ; while those that are spiral are clothed in a 

 very thin transparent sheath, as in Spirulina, Oscillaria, and Microcoleus. 

 The spiral torsion is especially strongly displayed in Sjnrulina, Spiral 

 hormogones are specially characteristic of terrestrial species. 



For the gelatinous substance of those cells which are in a resting con- 

 dition, viz. spores and the constituent cells of hormogones, the author 

 proposes the term cyanophycin. He states that, from a physical and 

 chemical point of view, it is identical with the gelatinous substance in 

 which the filaments themselves of the Nostochineaa are enveloped, and 

 believes it to originate from the walls of the cells ; it is probably a ternary 

 substance allied to starch. The colouring of the cell-contents is not due to 

 the presence of chromatophores ; in Nostoc ellipsosporum he was unable to 

 detect any nucleus, or only a very rudimentary one. A distinct connection 

 from cell to cell by means of very fine threads of protoplasm or of cyano- 



* Malpiyhia, i. (1886) pp. 74-83, 97-108, 145-60, 197-203 (1 pi.). 



