MO NOBLEPH ARID ALES 705 



In Monoblepharis sphaerica and M. hypogyna the oogonial rudiment 

 is formed first in a terminal position (Fig. 49 E, p. 704). After the 

 oogonium is delimited another more proximal hyphal segment is block- 

 ed off, which becomes the hypogynous antheridium (Fig. 49 F). Within 

 it, sperms are produced (Fig. 49 G) which escape in the usual manner 

 from a slightly exserted tubelike outgrowth immediately below the 

 oogonial septa. In M. macrandra the antheridia and oogonia first formed 

 are produced terminally on different hyphal branches (Fig. 53 E, p. 730). 

 As growth and reproduction proceed the diclinous habit is lost, and 

 oogonia and antheridia occur in various positions. If both organs are 

 formed on a single hyphal branch, however, alternating groups of one 

 or the other type of structure are usual. 



Maturation and escape of the antherozoids are accomplished in the 

 manner described for the zoospores. The antheridia, in contrast to the 

 sporangia, bear relatively few motile bodies (from four to eight). In 

 their shape, internal structure, and flagellation, these resemble the zoo- 

 spores (Fig. 50 G, p. 708). They are smaller, however, and, unlike 

 them, exhibit a pronounced tendency toward amoeboid movement. 



Further maturation of the oogonium involves the development of a 

 highly refractive apical receptive papilla (Fig. 50 A, p. 708). Coincident 

 with, or often before, the formation of this structure the minute evenly 



Explanation of Figure 49 



delimited; G, mature oogonium and antheridium. H-S. Cytological prepara- 

 tions of developing oogonia, fertilization process, and formation and ger- 

 mination of oospores of Monoblepharis macrandra (Lagerheim) Woronin (all?) : 

 H-I, beginning of formation of oogonium; single egg nucleus is already clearly 

 distinguishable; /, oogonium delimited by cross wall; enlarged nucleus has 

 not as yet migrated to apex of oogonium; K, mature oogonium with apical 

 nucleus ; L, mature egg in act of being fertilized by antherozoid ; nuclei of the 

 two gametes are clearly visible; deeper-stained areas may be seen in ooplasm, 

 as in preceding figure ; M, beginning of emergence of zygote from oogonium ; 

 the two nuclei lie in close proximity but are not as yet fused; N, the two 

 nuclei lying side by side in fertilized egg; O, portion of young oospore before 

 fusion of nuclei ; P, old oospore with single diploid nucleus ; Q, oospore after 

 winter rest period with resting diploid nucleus; R, binucleate stage previous 

 to germination; S, germinated oospore with multinucleate germ tube. 

 (A-G, Sparrow, 1933b; H-S, Laibach, 1927) 



