236 MASSACHUSETTS HORTICULTURAL SOCIETY. 



nuclei, and the mingling of cell contents in couingating forms — 

 where sexuality is doubtful, we find nothing parallel to this com- 

 mingling of nuclei, — and nowhere do we find it so thoroughly 

 promiscuous, and succeeded by an almost equally indefinite separa- 

 tion and distribution of nucleine. 



It is my purpose hereafter to continue more fully the study of the 

 action of the nuclei in the formation of the oospores. 



While at work on Saprolegnia, my attention was especially drawu 

 to what have been called resting zoosporangia. These present a 

 mouiliform series of enlargements at the free end of the hypha. 

 [Figs. 9 and 10.] They are formed by from two to six repetitious 

 of the process described by Rothert in his account of the formation 

 of the simple zoosporangium. The hypha ceases to grow in length, 

 while the protoplasmic contents continue to press toward the free 

 end of the hypha. This results in a terminal enlargement. The 

 protoplasm aggregates in this swelling and becomes densely gran- 

 ular. About the point where the hypha begins to enlarge, the dense 

 protoplasm grades into the thinner sub-sporangial protoplasm. In 

 this region a liyaloplasmic disc is formed A:)y the withdrawal of the 

 granules. From the basal portion of this disc a septum is pro- 

 duced, probably b}' material which is taken up and deposited by 

 the " cellulin corpuscles " which Rothert states accompau}' the for- 

 mation of the septum. In the meantime that portion of the hj^pha 

 immediately below the septum begins to enlarge, passing through 

 the same stages. This is repeated a variable number of times 

 (from two to six), the zoosporangial swellings growing snudler 

 proximal]}'. Portions of the filament are not infrequently cut off 

 without becoming enlarged at all. The protoplasm in these sporan- 

 gia arranges itself as an investment of variable jthickness about 

 the periphery of the cell, with granular strands or sheets extending 

 across the lumen, forming two or more vacuoles. This protoplas- 

 mic layer becomes finely granular and very dense, especially on its 

 external aspect. The surface bordering the tube is mucli more 

 coarsely granular, and contains nuclei. At this point the develop- 

 ment is arrested, and the zoosporangium has the power of remain- 

 ing quiescent for a considerable length of time without losing its 

 vitality. In several instances growth was induced after more than 

 a fortnight of rest. When stimulated to renewed activit}' by the 

 addition of fresh nutriment they showed capability' of developing. 



