* 19"] BARRETT— BLASTOCLADIA 



357 



masses of fatty protoplasm. Their true nature has not been deter- 

 mined, but, as will be shown later, they have at least one definite 

 function in connection with zoospore formation. They are always 

 present in more or less abundance, their extent of occurrence de- 

 pending, to a degree at least, on growth conditions of the plant. 

 In old plants, especially when the production of reproductive 

 bodies has ceased, large groups of such bodies may be seen 



collected near the pseudo-septa, and frequently elsewhere in the 

 mycelium. 



Bodies somewhat similar in appearance are known to occur in 

 the hyphae of members of the Saprolegniaceae. Pringsheim (5) 

 describes these at length and records a series of microchemical tests 

 to determine their nature. According to his conclusions they are 

 neither a proteid nor a carbohydrate substance, but rather waste 

 products of metabolism. 



Under favorable conditions of growth, a branchlet when ter- 

 minated by a reproductive body may continue its growth by the 

 production of a sub-branch (fig. 32). This sub-branch may be 

 likewise terminated, sooner or later, and continued growth repeated 

 as before. The length and rapidity of growth of these sub-branches 

 determines whether the reproductive bodies shall occur at intervals 



or less compact head or group (figs. 6, 7, 12). This 

 type of sympodial branching occurs in depauperate specimens of 



more 



Rhipidium 

 A podachlya 



It has also been noted 



Under the best normal conditions for growth, the production of 

 zoosporangia precedes that of resting sporangia. In pure cultures 

 this order is easily reversed by properly manipulating external 

 conditions. In a frequently refreshed culture, zoosporangia alone 

 are at first produced, while on the other hand plants in a culture 

 started and maintained in a small amount of water usually give 

 nse to resting sporangia only. 



The extent to which branching may proceed before the produc- 

 tion of reproductive organs varies greatly. This may continue 



until a well formed almost hemispherical tuft is produced, or on 

 the other hand zoosporangia may develop soon after the germi- 

 nation of the zoospore on the terminal end of the more or less 



