May, 1889. 
president's address. 
108 
them as they went eastwards. But this company did not 
return inland as the others had done ; like the party I had 
watched two days before, they rose in the air when they 
neared the point, and circling higher and ever higher, as if 
observing and considering, they at length began to disappear 
over the sea. I scrambled over a high loose stone wall, at the 
risk of breaking my bones, in order to reach a higher point 
and keep them longer in sight ; and then it was that I 
discovered that the Isle of Wight had arisen out of the 
mist since I last was within view of it. 
I shall refrain from commenting on these facts, and from 
any hasty conclusions that might be based on them as to the 
mental operations by which these birds conduct their travel, 
tiil I have tried to see more at the same place next autumn. 
But I think I have told a story which may possibly induce 
others to help me in my observations, whether they live in the 
Midlands or on the coast. Wherever they may be, they will 
probably see something worth noting, if they watch all 
Swallows and Martins any time in early autumn. 
BIRMINGHAM NATURAL HISTORY AND MICRO¬ 
SCOPICAL SOCIETY. 
PRESIDENT’S ADDRESS. 
(Continued from page 77.) 
Some curious results have been obtained in experiments 
upon the effects of various substances in stopping the growth 
of Bacteria. It is well known how difficult it is sometimes 
to get the larger species of Fungi to develop, and the same 
thing is true of the smaller kinds in a still higher degree. 
One of the most striking instances is found in the account 
which Raulin gives of Aspergillus niger ; this is not indeed 
one of the Schizomycetes, but it is a pathogenic fungus, and in 
some respects similar to them. 
To obtain the maximum growth no less than a dozen 
substances were needed : water, sugar, tartaric acid, nitrate 
and phosphate of ammonia, carbonates of potash and of 
magnesia, sulphates of zinc, iron, and ammonia, and silicate 
of potassium, all in constant and fixed proportions; the growth 
must also be maintained at a temperature of 35°C. and an 
abundance of moist air must have free access. The sulphate 
of zinc, e.g., enters into this medium in only infinitesimal 
proportion, but if it were not present the fungus grew poor 
and died. On the other hand, the addition of an infinitesimal 
