1886.] 



MICROSCOPICAL JOURNAL. 



189 



Special Reference to the Require- 

 ments of Forestry,' by B. E. Fernow, 

 of Washington, D. C. 



' Human Cerebral Fissures, their 

 Relations and Names,' by Prof. B. 

 G. Wilder, of Ithaca, N. Y. 



' The Lampi-eys of Cayuga Lake,' 

 b}' Professors S. H. Gage and L. E. 

 Meek, of Ithaca, N. Y. 



' The Facial Nerve in the Domes- 

 tic Cat,' by T. B. Stowell, of Cort- 

 land, N. Y. 



'Vaso-motor Nerves of the 

 Limbs,' by Prof. H. P. Bowdich, of 

 Harvard Medical School. 



' Areas of Form and Color Per- 

 ception in the Human Retina,' by 

 Prof. J. H. Pillsbury, of Smith Col- 

 lege. 



' Demonstration of an Easy Method 

 of Measuring Reaction Times,' by 

 Joseph Jastrovs^, of Philadelphia. 



' Relative Stability of Organs as 

 Dependent on Phylogeny,' by Dr. 

 Frank Baker, of Washington, D. C. 

 ' Physiological Notes on Ants,' 

 and ' The Dreams of the Blind and 

 the Centres of Sight,' by Joseph 

 Jastrow. 



' Work of the U. S. Dept. of Ag- 

 ricultui'e on Economic Ornithology 

 and Mammalogy,' and ' Do Any of 

 Our North American Bats Migrate ?' 

 by C. Hart Merriam,- of Washing- . 

 ton, D. C. 



' Travelling of the Larva of a Spe- 

 cies of Sarcophaga,' bv W. L. Cof- 

 tinberry. 



' Homologies of the Ear-bones of 

 the Lower Vertebrata,' by Prof. E. 

 D. Cope. *** 



o 



A New ' Synthesis ' of Pela^^ic 

 Organisms. 



BY DR. ASPER AND J. HEUSCHER, IN 



ZURICH. 



[Translated from the Zoologischer Anzeiger, ix, p. 

 448. 19 July, -86.] 



Since Weismann, in 1S70, showed 

 that it was possible in Lake Constance 

 to capture at night numbers of small 

 crustaceans, the same fact has been 

 demonstrated by Forel, Paresi, and 

 Asper for a large number of the 



Swiss and Italian lakes. The ' pe- 

 lagic ' fauna of these fresh -water 

 lakes consists of Cladocera and 

 Copepoda for the most part, with 

 also gnat larvae and mites. 



Dr. Imhof added considerably to 

 this fauna, viz : — The flagellate gen- 

 era Dinobryon^ Ceratium^ Peri- 

 dintum^ and Salpingoeca ; also xo- 

 iiiers Asplanckna^ Conochilus^ and 

 AimrcEa. 



Appointed by the Natural History 

 Society of St. Galler to investigate 

 the fauna of the alpine seas of the 

 Swiss Canton, we have, from the 

 beginning of this work, tested the 

 performance of an apparatus used 

 in the lake at Zurich. This 'pe- 

 lagic-net' was made of fine silk 

 bolting cloth, its meshes not meas- 

 uring more than 15 micro-millime- 

 ters. In the Zurich lake we found 

 as a gathering in this net a turbid 

 ye How -brown fluid, which re- 

 minded one of freshly-pressed cider. 

 Its microscopic stud}' revealed an as- 

 tonishing picture. Every drop con- 

 tained countless swarms of two spe- 

 cies of Dinobryon^ similar numbers 

 of Aster ionella forniosa Hass., 

 fewer specimens of Ceratiuvi hi- 

 rwidinella Miiller, and Anurcea 

 foliacea Ehrenb., A. longi spina 

 Kellic, and Asplatichna helvetica 

 Imhof, TriartJira longiseta Ehr., 

 Polyarthra Trig/a Ehr.. some He- 

 liozoa, and representatives of the Di- 

 atom genera, Fragilaria, Synedra, 

 Nitzschia, Surirella, etc. 



We have taken pains to deter- 

 mine the approximate number of 

 rarer forms contained in the net. 

 After the net had been drawn 

 through 300 meters the contents 

 wei'e collected in 200 c. c. of water, 

 and from it a dropping tube was 

 filled, a previous experiment hav- 

 ing determined that 15 drops were 

 equal to i c. c. One drop was found 

 to contain : — 

 10 Anurcea foliosa Ehr. 

 8 Afiurcea longispina Kellic. 

 60 Ceratium hirundirtella Miiller. 

 The Dinobryo7i and Asterionella 



