CHAPTER V. — COMPARATIVE REVIEW. — USTILAGINEAE. I 79 



series of forms. Here we may have formation of sporidia according to one of 

 the above modes or one like them, but without their conjugation, as in Ustilago 

 Maidis, U. Vaillantii, U. longissima, and in Entyloma Magnusii, Wor. ; or there is no 

 formation of sporidia, but production of a germ-tube from the resting-spore which 

 shows the growth of an incipient mycelium without conjugation of any of its segments, 

 as in Sorosporium Saponariae according to Woronin. 



The germination of the resting-spores in the nutrient solutions mentioned 

 on p. 127 has been recently studied by Brefeld in great detail. In some species it is 

 easier and more rapid in these solutions than with only a supply of pure water, and 

 generally so far differs from the process as described above, that luxuriantly vegetating 

 forms take the place of the short-lived products developed at the expense of the 

 protoplasm of the spore, and that these can continue to grow on without change of 

 shape and without limit if supplied with sufficient nutriment. The form which they 

 assume depends on the species ; either the promycelium which begins in the manner 

 above described continues to develope like the Sprouting Fungi (see page 4), or the 

 germ-tube of the resting-spore grows into a branched filamentous mycelium from 

 which spores are then abjointed in the fluid itself or on branches which rise into the air. 

 Ustilago antherarum, U. Carbo, U. Maidis, and U. Kiihniana are beautiful examples of 

 the sprouting form ; U. destruens of the sporogenous mycelia. 



There are species intermediate between the two forms, a detailed account of 

 which will be found in Brefeld. U. destruens itself may to some extent be regarded 

 as an intermediate form, since some of its spores germinate by sprouting in the 

 nutrient fluid, while others develope a mycelium which vegetates and ramifies in the 

 fluid, and sends up erect branches into the air from which elongated spores serially 

 developed as branched chains of sprouts are abjointed (see p. 66). In the case 

 of Tilletia Caries, Entyloma, and Thecaphora Lathyri the resting-spores have not 

 been seen to germinate in a nutrient fluid, or the product of the commencing 

 germination soon dies away ; on the other hand when primary or secondary sporidia 

 from plants which have germinated in water are placed in nutrient solutions, there is 

 a copious formation of mycelium and acrogenous abjunction of spores on erect 

 aerial branches of the mycelium ; these spores in Thecaphora are like the primary 

 sporidia of germination in water, those of the other species mentioned are like the 

 secondary. 



Geminella Delastrina differs from the rest, as Schroter found, in the acrogenous 

 serial abjunction of roundish sporidia on the short promycelial tube in water ; the 

 further development of the spores was not observed. The same species produced 

 large mycelial bodies in Brefeld's nutrient solutions, but their further history also was 

 not ascertained. 



Section LVII. Finally, in some Ustilagineae spores of another kind are 

 produced on the mycelium forming the resting-spores and inhabiting the host-plant ; 

 these may be termed provisionally gonidia. Schroter found that in a number 

 of species of Entyloma, E. Ranunculi for example which is common on Ranunculus 

 sceleratus and R. Ficaria and especially E. serotinum on Symphytum officinale, the 

 mycelium which lives in the leaves sends a large number of short branches 

 often closely crowded together into the air, partly through the stomata, partly through 

 the lateral walls of the epidermis, and that from the extremities of these branches 



N 2 



