PLATE IV. 



Figure 52. Phycomyces nitens showing zygosporic lines at regions of contact 

 between (-|-) and (— ) strains. Tlie vegetative differences distinguishing the two 

 strains are but slightly indicated in the photograph. 



Figure 53. Mucor v. Zygosporic lines with light areas in their centre made up 

 of zygospores in arrested stages of development. 



Figure 54. Mucor vi. Zygosporic lines. ♦ 



Figure 55. Mucor Muredo. Zygosporic lines. 



Figure 56. Mucor i and Mucor v (+) and (— ). Lines of hybridization between 

 a homothallic and a heterothallic species. 



Figure 57. Mucor v and Mucor n. Zygosporic line between (+) and (— ) 

 strains of Mucor v and lines of hybridization between the opposite strains of 

 Mucors V and n respectively (cf. diag. p. 212). 



Figure 58. Mucor in. A striking difference in habit is shown between the 

 (+) and (— ) strains which are forming zygospores at their regions of contact. 



