CHAPTER V.—COMPARATIVE REVIEW.—-USTILAGINEAE. 179 
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. Kühniana 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 Schröter 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 gonzda. Schröter 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 
