NOTES AND MEMOBANDA. 



449 



2. A Chytridiacea parasitic on FloridecB. — In the tissue of Eucheuma 

 isifornus (from Key West) were observed cells of a difierent character 

 from those of the tissue of the seaweed, and presenting the nearest 

 resemblance to those of a Chytridium already known as a parasite on 

 Desmidieaj.* 



3. AsterosplioericB parasitic on Mesocarpus scalar is. — These occur in 

 the form of minute globular cells found in pairs within the cells of 

 the Mesocarpus, one of each pair being usually smooth, and the other 

 covered with spines. When the parasite is fully develoijed, the 

 infected cell of the Mesocarj)us is swollen into the form of a bladder, 

 and all its pr(jtoplasmic contents have disappeared. The parasite 

 probably enters in the form of a zoospore which pierces the cell-wall 

 of the host, the orifice subsequently again closing up. The green 

 colour of the infected cell gradually disappears as its protoplasm is 

 absorbed by the parasite. Ultimately a kind of conjugation takes 

 place between the smooth and spiny parasitic cells, the contents of 

 the former passing into the latter. The ultimate fate of these latter 

 is uncertain, and it is possible they may be merely stages in the 

 development of some higher organism. 



4. Nostochacece and Oscillatorie<B in Gromia and in the Ova of Fresh- 

 water Snails. — An Oscillatoria is not uncommon within the siliceous 

 carapace of Gromia, consisting of a coiled filament with a diameter of 

 about 0*0084 mm. The two ends grow slowly, it is not enclosed in 

 a gelatinous sheath, and is probably a Hypheothrix. In another 

 species of Gromia a much coiled filament was observed completely 

 filKng its cavity, apparently a Cylindrospermura ; it had abundance 

 of chronospores. The ova of a small fresh-water snail found on the 

 leaves of a Potanogetou, enclosed in a thin transparent calcareous 

 shell, and about • 13 mm. in diameter, were found to contain well- 

 developed sporiferous filaments of a Spermosira ; the spherical or 

 elliptical spores, -0056 mm. in diameter, were double that of the 

 filament. The parasite had apparently developed after the escape of 

 the young mollusc from the shell. 



5. Anahcena and Chlorococcum, in the perforated Cells of Sphagnum, 

 — The green spherical cells of these two algfe were found in the 

 large colourless empty cells of Sphagnum latifolium from Cape Cod. 

 As the diameter of the smallest of them was double that of the per- 

 forations of the Sphagnum cells, they must have developed in that 

 situation. 



6. Anahcena in the Leaf of Azolla canariensis. — The hollow of the 

 leaf of Azolla is, in at least one case out of three, filled with filaments 

 of an Anabtena, which can only have penetrated from without through 

 the open channel into the cavity. 



7. Oscillatoria parasitic in the Oogonium of CEdogonium. — This 

 is one of the most singular cases of parasitism. The specimen, 

 apparently one of CEdogonium Bothii, had a well-developed, perfectly 

 closed oogonium of normal structure, into which had penetrated 

 a twice-coiled Oscillatoria-filament, probably a Hypheotbrix. As 

 the oogonium was perfectly closed, the parasite must apparently have 



* Reinscl), in Pringsheim's ' Jahrb. f. wiss. Bot.,' xi. 18. 

 VOL. II. 2 G 



