MISCELLANEOUS OBSERVATIONS ON HYDRA, WITH SPECIAL REFERENCE TO REPRODUCTION. LIBBIE H. HYMAN, HULL ZOOLOLGICAL LABORATORY, UNIVERSITY OF CHICACO. The following observations have accumulated during several years' cultivation of hydra in the laboratory together with numer-ous collections of the animals from nature. The taxonomy employed is that of Schulze ('17) who has made a much needed revision of the hydras and furnished adequate de-scriptions of the known species. He divides them into three gen-era : Chlorohydra, with symbiotic algae in the entoderm ; Pclma-tohydra, column differentiated into body and stalk; and Hydra, sensu strictu, column not so differentiated. The common green Hydra then becomes Chlorohydra I'iridissinia ( -= Hydra viridis-siina Pallas, Hydra 1'iridis Linnaeus) ; the brown Hydra is des-ignated as PclinatoJiydra oligactis ( = -Hydra oligactis Pallas, Hydra fused Linnaeus, Hydra dia'da Downing) ; and the genus Hydra contains a number of species some of which in the past have been confused under the name of Hydra vnlgarls ( --Hydra grlsea Linnaeus). There are at least four, possibly five, species of hydra around Chicago, of which one does not correspond with any of Schulze's descriptions and requires to be named and de-scribed. The observations in this paper concern Pclinatohydra oligactis (Pallas) Schulze and Hydra stcllata Schulze. CULTIVATION. The cultivation of hydras in the laboratory is not difficult, pro-vided sufficient food is available. The real problem is therefore the maintenance of an adequate food supply. Daphnia or other daphnids furnish the most convenient food and are raised as fol-lows. Several dishpans or tubs are partly filled with well-aerated water. To each is added a sufficient amount of boiled aquatic 65
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