1898.] Swan. — The Gemis Leptotegnia. 35 



The only allusion I have seen to chlamydospores, at all 

 resembling those which I have described, is made by 

 Humphrey, as occurring in the investigations of Zopf on 

 Apodachlya pyrifera ; these are described as " sometimes 

 lateral in position and never produced in chains." 



On the conditions which determine the production of 

 chlamydospores, and their function, considerable difference of 

 opinion exists. They are not developed on all species, and 

 vary much in form, even on the same plant, while their 

 appearance is also quite uncertain on several species which 

 are known to occasionally produce them. From favourable 

 observation and some previous experience, I am not able to 

 regard the chlamydospores of L. bandoniejisis as constituting 

 a special form of intermediate resting spore-reproduction, 

 which Humphrey suggests, as their ready germination would 

 not allow them to fill such a want, even supposing the 

 provision were necessary^. 



The chlamydospores of L. bando7iie7isis appeared to me as 

 forms of abnormal vegetation arising from oogonial or spor- 

 angial origins, and due to unusual surrounding conditions 

 probably never present in a state of nature. Such forms are 

 comparable with the so-called involution forms of bacteria, 

 which are also produced when the conditions of culture are 

 unfavourable. In the Saprolegniacese generally speaking the 

 sexual and non-sexual fruit is produced at different periods 

 with a varying interval of time between them. It is only 

 after the protoplasmic material which goes to build up the 

 zoospores is exhausted, and a time of rest for further nutrition 

 has elapsed, that the sexual oospores are developed. If the 

 interval of time between these periods be well marked (and 

 such as will follow rigid attention to air supply, uniform 

 temperature, and other conditions), chlamydospores are not 

 normally produced, although this period is the very time at 

 which they generally appear. 



When, however, the conditions are not favourable, the 

 interval may be so short as to cause an overlap in the sexual 



* Diplanetic zoospores were found by De Bary (" Morphologic der Pilze," 

 p. 369) to retain their vitality for weeks, while Fischer (Rabenhorst's 

 " Kryptogamen-flora)" p. 317) found spores of the Saprolegniaceae in 

 springtime from lately thawed w^ater, which must have remained torpid 

 for months, and 3'et promptly germinated. 



