ZOOSPOEES IN THE SAPROLEGNIE^. 427 



On the Formation and Liberation of the 

 Zoospores in the Saprolegnieae. 



By 



niarcus ]fl. Hartog, D.Sc, M.A., F.R.U.I. 



I. The Formation op the Zoospores. 



The zoosporange of the Saprolegnieae has long been a 

 favourite object for the study of cell development ; but only 

 within the last few years has an insight been obtained into the 

 great complexity of the phenomena attending the formation 

 and the liberation of the zoospores. These were first described 

 by Biisgen (''Die Entwicklung der Phycomyceten-sporangien" 

 in ' Pringsheim's Jahrbiicher/ vol. xiii, 1882);^ and, a little 

 later, independently by Marshall Ward ("Observations on 

 Saprolegnieae " in ' Quarterly Journal of Microscopical Science/ 

 N. S., vol. xxiii, 1883). 



The following is an abstract of the nearly concurrent results 

 obtained by these two observers. As is well known, the 

 zoosporange is formed by the enlargement of the end of a 

 hypha. The protoplasm streams into this enlargement and 

 becomes dense, its transverse septum then isolates the zoo- 

 sporange, which contains one large centre vacuole, or, in 

 Achlya, often several small ones. A blunt beak-like enlarge- 

 ment forms at an undetermined place (usually the apex), and 

 through this the spores are finally emitted. 



In Achlya the following processes occur. There appears in 



' This paper contains an excellent summary of the literature of the subject. 



