282 



\ AHIA'DONN oy THE ISPOKOC'YST IX SAPROLE(iXIA, 



In the opinion of the writer tlie al)ove is the true DictiiudiuH couditiou, that 

 described by Leci'.niere being a transitional stage to this condition. 



In addition to a true Dictyuchun and a true Aplanes condition, an interesting 

 transition often occurs which combines the featui'es of both these types. In cer- 

 tain sporocysts a number of encysted spores germinate directly, producing long 

 narrow tubes resembling young hypliae. which penetrate the sporoeyst wall. 

 Other encysted spores, within the same sporoeyst, after producing a cyst tube, 

 cease to germinate and enter u])on a Dicti/iichus condition, the second motile 

 phase taking place with the liberation of a zoospore from a broken cyst tube 

 (Text-fig. 6) . This type of sporoeyst is a combination of that where all motility 

 is suppressed (Aplanes) with one in which the second motile phase is present, 

 although noticeably feeble and short in duration. It is interesting to note that 

 transitional form-i occur, between the true Dictiiucln(s conditioii, through com- 

 posite sporocysts where either the Dictyuchus or Aplanes condition is predomin- 

 ant, to the pure Aplanes form. It is suggested that this composite sporocy.st 

 should lie known a'; tlie "Dicti/ii-Aplaves" condition. 



Text-fig.8. Club-shaped sporoeyst of the Aplanes form. Swollen structures at "a" 

 and "b" ai-e formed by the streaming of the protoplasm towards the tip of the 

 germ tube, (x 230). 



Text-fig. 9. Shows formation of two germ tubes in terminal swelling after streaming of 

 protoplasm has ceased, (x 230). 



Rare examples of composite sporocysts are found, in which the features of 

 Achli/a, Saprolegnia, Dictyuchus and Aplanes are eoipbined. In Text-fig. 7 the 

 Achhja type of branching is shown. The main sporoeyst is of the "Dictyu- 

 Aplanes" form, while the two basal sjiorocysts are normal Saprolegnia sporo- 

 cysts incompletcl ,- disduirged. 



