176 LAKES AND RIVERS, 



placed under the microscope. On examining the 

 figures in Cornu's monograph, I am convinced that 

 they represent a stage of development of the Sapro- 

 legnia. 



"Mons. Max Cornu, in his 'Monographic des Sapro- 

 legniees' in Annales des Sciences Naturelles, 1872, 

 says, the family of the Saprolegnia constitute a natural 

 group of aquatic fungi, to which species have been 

 added from time to time. The principal writers on the 

 subject have been German, such as Schlieden, Unger, 

 Braun, Pringsheim, de Bary ; and M. Muret, a French- 

 man, has also written briefly on the subject, and has 

 given good and accurate drawings which better illus- 

 trate the subject than lengthy verbal description. But 

 according to MM. de Brongniart and J. Decaisne no 

 general work has yet been published, for the above- 

 mentioned authors have only written short comments 

 on these fungi, which are scattered throughout various 

 periodicals. The difficulty of studying these genera 

 is great, for they can only properly be observed when 

 in a living state. The rapidity of their growth, their 

 short lives, and rapid decay make the procuring of 

 them in the proper state a difficult matter. M. Brong- 

 niart says he met with some of these species which 

 had been previously described ; he himself discovered 

 others not described, and felt convinced that many 

 yet remained still unknown. He considered the 

 manner of reproduction and method of propagation 

 to be the most important points for observation. 

 Learned men still differ much on these points. M. 

 Cornu says the germs may be disseminated either 

 through the air or through water ; thus showing that 



