364 BOTANICAL GAZETTE [November 



tion was correct. Fig. 9 shows a section through an immature 

 papilla and the adjacent wall of the ^oosporangium. It is very 

 evident that the wall is single, but that there are two distinct parts 

 to the gelatinized plug of the papilla. The plug has a strong 

 affinity for stain, especially safranin. The ungelatinized part of 

 the wall is seen as a thin unstained layer extending over the convex 

 plug. The wall immediately surrounding the papilla is thickened 

 so as to form a sort of collar. . This is clearly seen in empty 

 sporangia. Fig. 10 shows the two parts of the plug separated as a 

 result of cutting the section. It will be seen that the inner portion 

 bears a close relation to the protoplasm. Such a section is common. 

 In those sections which show a contraction of the protoplasm from 

 the wall of the zoosporangium, almost invariably it is found to 

 adhere closely to the inner part of the plug, whether that remains in 

 place or not. It is this part of the plug that has the less refractive 

 power in the living state and that on stretching out forms the 

 vesicle referred to above. Very probably gelatinization is brought 

 about by the action of an enzyme secreted by the protoplasm in the 

 region about the papilla, which may account for the close relation 

 between the two just described. Apparently the outer part of the 

 plug becomes more thoroughly gelatinized than the inner, while 

 the outer thin unstained part of the wall over the papilla is little 

 or not at all affected. 



This condition may be explained, it seems, by assuming that 

 the wall of the zoosporangium is made up of lamellae which differ 



composition 



.lnizin 



This assumption is strengthened by the fact 

 that in a few sections the condition illustrated in fig. 9 was observed, 

 that is, the line separating the two portions of the gelatinized plug 

 extended slightly into the sporangial wall. 



Development of resting sporangia 



The resting sporangia agree in general to similar bodies described 

 by Reinsch (6) and Thaxter (9) for B. Pringsheimii, and by 

 Thaxter (9) for B. ramosa. In B. Pringsheimii they are called 

 resting spores by Thaxter, and are considered as doubtful oospores 

 by Reinsch. They are indicative of the older condition of the 



