86 



COMPARATIVE MORPHOLOGY OF FUNGI 



cance is still obscure; possibly it is the dynamic center of the poly- 

 energid egg or an organ of nourishment for the nucleus. 



In the antheridium also the nuclei go through two mitoses (Fig. 52, 4) ; 

 the conjugation tube penetrates to the vicinity of the coenocentrum, 

 dissolves at the tip and about 100 nuclei enter the egg; they approach 

 the female nuclei and slowly fuse with them (Fig. 52, 5 and 6). Here- 

 upon the fertilization tube and the coenocentrum are dissolved, the egg 

 is surrounded with an exospore near which a primary and a secondary 

 endospore are laid down. 



Fig. 53. — Albugo Tragopogonis. 1. Antheridium and oogonium with mitoses. 2. 

 Nuclei near the coenocentrum dividing while the peripherial nuclei of the egg degenerate. 

 3. The rest of the egg nuclei except one, degenerating. 4. A male nucleus enters as the 

 female approaches the coenocentrum. Albugo Candida. 5. Penetration of copulation tube. 

 One nucleus remains in egg cell while the others migrate to the periplasm. 6. Fusion of 

 male and female nuclei. (After Stevens, 1901.) 



Two species, A. Tragopogonis (Stevens, 1901) and A. Ipomoeae- 

 Pa?iduranae (Stevens, 1904), correspond, as far as the maturation of the 

 coenocytic egg, with A . Bliti. Of the 100 potential sexual nuclei only one 

 is functional; it lies next the coenocentrum, develops to four times its 

 original size when in A. Tragopogonis, the other nuclei dissolve (Fig. 53, 3 

 and 4) or, in A. Ipomoeae-Panduranae, migrate to the periplasm. From 

 the equally multinucleate antheridium, one or more nuclei enter the egg 

 (Fig. 53, 4) ;. one of them fuses with the female nucleus while the others 

 are dissolved. The diploid nucleus soon divides repeatedly so that 

 the oospore winters over with 30 to 40 nuclei. 



