274 H. MARSHALL WARD. 



Schmitz has described nuclei in these and allied fungi, as well 

 as in many others of the lower cryptogams.^ I have lately 

 also found nuclei of a very definite character in the mycelium 

 of an allied fungus, and shall show that a perfectly definite 

 division of nuclear masses occurs in the zoosporangia of 

 Achlya and Saprolegnia. It is at least certain that the 

 Saprolegnise can no longer be regarded as devoid of nuclei, 

 and the same probably holds good for all but the very lowest 

 cryptogams; according to Schmitz the Phycochromaceas and 

 Schizomycetes. 



The reproduction of the Saprolegnise takes place by 

 means of asexual zoospores, produced in long zoosporangia ; 

 and sexual (at least morphologically they must be considered 

 so) oospores, produced in oogonia, with or without accom- 

 panying antheridia. The details concerning both these 

 kinds of structures may be deferred for the moment. 



With this introduction, the immediate object of the present 

 essay may be entered upon ; that is, to describe some observa- 

 tions made during the past summer and autumn on species of 

 Achlya and Saprolegnia, the two most important genera of 

 the group. These observations are not all equally valuable or 

 new (although some of the facts were observed before I was 

 aware that others had discovered them),^ but they have been 

 made quite independently of the literature,%nd are thus of some 

 service as confirmatory evidence to those who wish to study the 

 subject further. 



^ ' Sitzber. d. niederrlieiu Gesel. iu Bonn,' 1880. Quoted also in the 

 appendix to the recent Engl, trans, of Sach's ' Textbook.' 



2 I must take this opportunity of thanking Prof. De Bary, not only for 

 giving me material, but also kind advice and references in connection with 

 this work. 



^ The now copious literature consists chiefly of the following, among 

 others : — Pringsheim, several papers in ' Jahrb. fiir wiss. Bot.,' i, ii, and ix. 

 De Bary, Jahrb. f. wiss. Bot.,' ii. Walz, 'Bot. Zeit.,' 1870. Cornu, 'Ann. 

 dc. Sc. Kat., S. V.,' vol. xvi. 



The most important meiVioir, from a general morphological point of view, is 

 De Bary, ' Beitriige zur Morph. u. Phy. d, Pilze,' 1881. 

 ^ Sec also Huxley on " Saprolegnia iu llclatiou to Salmon Disease," this Jour- 

 nal, July, 1882. 



