146 МВ. A. ВАВСГАУ ON THE LIFE-HISTORY 
TELEUTOSPORES.— These are brown single-celled bodies ( Uromyces), usually distinctly 
thickened at the free end, through which a germ-pore may often clearly be seen. They 
may be scraped off their beds without much difficulty, breaking off with a portion of 
stalk adhering to them. Оп an average they measure, when just moistened, 36 x 20 и 
but individual measurements varied from 26 x 24 u to 44x 18 и. The mean thickness of 
the wall of the spore is 2 и, but at the free end where it is thickened it measures 6 to Зи. 
Most of the spores are oval and symmetrical, but a few are asymmetrical, with the 
thiekening to one side. In some a nuclear space is clearly defined in the midst of 
granular protoplasm. The spores, asa rule, do not germinate immediately after ripening, 
although in a very few cases I did observe such germination. After a winter rest, how- 
ever, they germinate freely in water, emitting a promycelium of the usual characters, 
dividing by septa into three cells usually, but sometimes four. I have observed the 
germination of these spores from early spring to July, when in nature they attack the 
newly-formed leaves. In April they germinate feebly and slowly; in May still only a 
few germinate, and that slowly; even in June some halting in germination may be 
observed; but in July germination is very speedy. 
The diameter of the promyceliun is about 8 и. Each cell usually produces a sporidium 
at the end of a sterigma, which is about 14 и in length and 2 и in diameter. The spori- 
dium is oval, and very often displays two vacuoles, one at each end; it measures from 
12X8p to 14х10. Тһе sporidia germinate quickly, forming secondary sporidia, 
sometimes even before they become detached from the promycelium (fig. 12, РІ. I.). 
The germ-tube of the primary sporidium is somewhat stouter than the sterigma, 
measuring usually Зи in diameter. Тһе secondary sporidium is generally about the 
same size as the primary; in one case, carefully measured, it was found to be 
14X10, exactly the same as the primary sporidium which gave rise to it. І noticed 
that very soon after the ecidial attack had established itself the old teleutospores of 
the previous year lost vitality, and were no longer capable of germinating——i. e. during 
September. 
_ Since my return to Simla, in 1889, I have been able to eonfirm the one successful 
experiment, above mentioned, in which the zcidium was produced with sporidia. On 
the 5th June I placed some sporidia on the young tender leaves of two plants, (a) a twig 
cut off under water and kept in a glass box outside, and (0) a small rooted plant in a pot 
kept under a glass shade in my laboratory. Тһе sporidia were obtained thus :— боше 
teleutospores were зстарей off on the 3rd J une, and floated on water in a watch-glass, 
which was then kept in a moist atmosphere. On the 5th a fairly large number of 
sporidia eould be seen with a microscope. This water was placed on the leaves of the 
two plants. On the 12th (7 days), (б) showed two leaflets distinctly attacked, and a few 
days later seven distinct centres of attack. Unfortunately the plant got injured, and the 
shoot bearing these zecidial patches died off on the 4th July, just as a number of æcidia 
were about to emerge. The leaves of (а) similarly disclosed several foci of attack, which, 
however, did not proceed to any :cidial formation, as, being merely cut twigs, they 
withered soon after initial patches were formed. Again, on the 15th J une, I placed 
