BIRMINGHAM MICROSCOPICAL SOCIETY. 305 
who search ponds for this and other free organisms do not take the 
necessary means to find out whether it is present or not, and unless 
a few dips suffice to secure specimens it is at once settled that the 
thing is not there. 
The explanation is that Volvox is greatly stimulated by light and 
warmth, as is usually the case with plant life, and under these 
favourable influences it will not only increase at a great speed, but 
will roll through the water in every direction, so that the most hap- 
hazard dip with a bottle is sure to secure specimens ; and I have 
many times seen it even covering the banks like a green scum 
where the water has receded and left it stranded, as we see marine 
objects on the sea-shore. 
But in winter or times of extreme cold it makes its retreat from 
the ‘ weather” side of the water, and is to be sought very near the 
bottom in some shallow part where the weeds not only give it 
shelter, but find it anchorage too ; and knowing these spots at my 
particular hunting-grounds, I have often stood upon the ice and, 
after breaking a hole with a hammer, dipped in my bottle or swept 
beneath with my canvas net and gathered it in any desirable 
quantity. 
Of course it may happen that the particular patches of weeds 
among which it is snugly nestling are out of reach unless we are 
equipped with water-tight boots and prepared to risk their efficacy 
for keeping the feet dry ; but, though I do not wish to impress 
upon you that I think when it is once present it always remains so, 
I am sure a more thorough search will prove that the vagaries with 
which this organism is credited are only the fancies of the in- 
sufficiently persevering pond-hunter, and that there is no period of 
the year when it is not to be found. 
If we make a sudden jump from the Vegetable to the Animal 
Kingdom, perhaps there are few creatures of more general interest 
and beauty than the thecated rotifers, Floscularia, Melicerta, 
Cicistes, etc., and a study of these indicates beyond a doubt that 
in active life they require a plentiful supply of decayed vegetable 
matter with which to build up their tiny structures, and, as 7 shall 
show you, I have made good use of this knowledge in collecting 
and keeping them afterwards. 
Next to these, perhaps, should be placed that most beautiful of 
the free rotifers, ‘Motommata Brachionus, which came to my hands 
in abundance in the following instructive way. 
I was driving along a country road, with a keen eye for likely 
ditches or puddles, when I came to a heap of rubbish with just a 
small patch of water at its base not more than three inches deep in 
the wheel-ruts or holes made by the feet of cattle. 
This I thought worth trying, and to my surprise found it contained 
Pandorina morum, and that charming rotifer before named. 
