1900] MICROSCOPICAL JOURNAL. 145 



Miscellaneous Notes on Microscopy. 



JOHN. H. COOKE, F. L,. S., F. G. S. 



Microscopy and Micro-technique. — This, by Dr. Al- 

 bert Schneider, of the Northwestern University, is another 

 work which we can confidently recommend to our readers. 

 The self-explanatory title enables us to dispense with a 

 description of its aims. It embodies many facts and sug- 

 gestions resulting from long observation and a very vari- 

 ed practical experience; and it is especially suitable as a 

 work of reference for all who are interested in biological 

 research. 



Plankton. — Mr. C. 0. Kafoid, of the Illonois Biologi- 

 cal Station, has devoted, during recent years, considera- 

 ble attention to the biology of the plankton ; and his in- 

 vestigations have shown that the Henson method of col- 

 lecting with a silk net, a"s usually practiced, is very faulty 

 and likely to lead to erroneous conclusions. The leakage 

 of the planktons through the yielding meshes of the silk 

 caused by their struggles and the pressure of the filtering 

 water, is so considerable as to give rise to grave errors 

 in the final computations. A considerable volume of the 

 plankton is lost at all seasons of the year, and in some in- 

 stances the actual catch of the silk net is but a small frac- 

 tion of the total present. The plankton thus lost is com- 

 posed very largely of minute algae, which constitute a fund- 

 amental link in the cycle of aquatic life. To prevent 

 these losses he now employs a filter made of filter paper 

 No. 575, Schleicher and Schull. It is very free from lint, 

 and does not easily tear when wet. As the filtering pro- 

 ceeds, the plankton is condensed in the bottom of the fun- 

 nel by means of a fine spray from a hand bulb. The meth- 

 od is very simple and rapid, and it yields from 75 per 

 cent to 80 per cent of the planktons, as compared with 

 45 per cent to 50 per cent with the silk net. The Henson 

 method answers well enough for the larger forms, such as 



