MONOBLEPH ARID ALES 701 



but gradually become more rounded. During this process of cleavage 

 all the protoplasm may not be used up in the formation of the spores, 

 and small bits may remain in the sporangium after discharge. By the 

 deliquescence of the tapering apex of the sporangium a circular, some- 

 times angular, pore is formed, through which the swarmers creep in 

 amoeboid fashion to the outside medium. The zoospore remains adher- 

 ent by its flagellum to the mouth of the sporangium for a varying length 

 of time and may oscillate for some little while before finally becoming 

 disengaged. In the meantime other spores may continue to emerge, and 

 it is not uncommon to see three or more thus attached to the orifice of 

 the sporangium (Fig. 48 A-B). The zoospore at this stage exhibits an 

 almost homogeneous content, in which are imbedded a few refractive 

 granules. Ultimately, by a quick succession of vigorous jerks it becomes 

 entirely free from the sporangium, and either immediately darts away or 

 floats for a time, feebly lashing its flagellum. This appendage, which is 

 about four or five times the length of the diameter of the spore body, 

 slowly increases its rate of vibration and, trailing behind, propels the 

 spore in a smooth gliding but lively fashion through the water. After 

 complete discharge of the zoospores further sporangia may be formed 

 by cymose branching of the hypha or, in Monoblepharis regignens and 

 occasionally in M. sphaerica and M. ovigera, by proliferation through 

 the empty sporangium. 



Recently discharged zoospores undergo a remarkable transformation, 

 for the internal structure, at first nearly homogeneous, assumes such a 



Explanation of Figure 48 



A-B. Discharging zoosporangia of Monoblepharis macrandra (Lagerheim) 

 Woronin. C-E. Freehand drawings of moving zoospores of Monoblepharis 

 polymorpha Cornu, showing internal structure. F-K. Cytological preparations 

 of developing sporangia in Monoblepharis macrandra (Lagerheim) Woronin : 

 F, tip of hypha before initiation of sporangium formation; G-H, young spo- 

 rangia before formation of basal cross walls; nuclei have increased in number 

 and some are paired, possibly as a result of a recent division ; /, sporangium 

 with basal cross wall laid down, separating it from hypha; nuclei are more 

 regularly distributed in cytoplasm; J, vacuole formation delimiting spore 

 initials; K, further differentiation of zoospores; dark-staining material is 

 present in cytoplasm in vicinity of nuclei. 



(A-E, Sparrow, 1933b; F-K, Laibach, 1927) 



