THE REPRODUCTION OF ASCOMYCETES. 
133 
active, in a measure, as one removed further away. At the centre 
and then at a certain distance from the borders, none of the spores 
presented any development. This absence of development ought 
not to be attributed to anything else than the want of air : the 
germ filaments, as well as the spores, have need of oxygen in 
order to increase. 
Numerous examples show, besides, that the spores at times aug- 
ment in a very considerable manner ; that they can then change in 
form, so as to be quite unrecognisable again. 
After many fruitless attempts, I think I saw that certain sper- 
matia were considerably modified in their form and size ; they were 
all situated upon the same side of the preparation, in an angle, 
right at the side of the gummed label, upon which was written the 
name of the species experimented upon, and the date of the sowing. 
The excess of water had dissolved some little of the gum, the 
presence of which having determined this considerable modifica- 
tion, which, for many reasons, was not extensive. The idea then 
struck me of giving the spermatia no more pure water, but a 
nutritive liquid. The spores of Mucor do not germinate freely in 
pure water whilst a centieme of sugar determines their develop- 
ment. 
In order to make the spermatia germinate which the more 
generally accompany the Diplodia acerina^ the following course 
may be adopted : a stick of Acer pseudo- Platanus was thrust into 
water, and a filtered drop of the liquid thus obtained received 
many spermatia ; the temperature was from 8 to 10 degrees about. 
In about five days, in the midst of a very great number of 
bacteria, one could see well at some points of the preparation 
many short filaments, thick, misshapen, and of a size so different 
from that of the spermatia that I could scarcely have reported 
them to be the same species, if I had not been prevented by the 
observations made upon other spores. The intermediaries were 
seen ; but it is necessary, in order to remove all. these doubts, to 
repeat the experiments under more suitable conditions. 
Two things were particularly unfavourable. These were: — 
1st. — The want of air in a preparation covered by glass. 
2nd. — The presence of numerous bacteria and of various muce- 
dines, introducing themselves by the sides of the preparation ; the 
bacteria were, above all, unfavourable, because of the small 
dimensions of the spermatia, which one may confound with certain 
developments due to the bacteria. 
We will here explain how it was possible to change, at least 
partially, these so disadvantageous conditions. One requires some 
cellules formed of a glass tube, or of lead cut perpendicularly on 
its axis and round, following two parallel and slightly different 
planes, and glued by one of these sections upon the slide. These 
cells are like those which M. Van Tieghem used for his culture of 
