380 The Upper Elf Loch, Braids. [Sess. 
young for several generations, while all the time not a single 
male may be observed. For this reason the female Daphnia 
has been regarded as parthenogenetic. The appearance of the 
males is not only irregular, but is also not limited to the 
autumn and winter months, as some have supposed. As a 
matter of fact, we have obtained them in July as well as in 
December, and they were even more numerous in the warm 
than in the cold months. 
The young Entomostracan is usually very different in 
appearance from the adult, but in some groups the difference 
is less apparent than in others. One of the most interesting 
groups, in this respect, is that of the Daphniade, as:some of 
them, and Daphnia especially, are subject to so much variation 
that there is still considerable doubt as to which are species 
and which mere varieties. Development and environment 
appear to have a modifying influence on the form of the 
Daphniz, and even in some degree on their structure also, to 
a greater extent than on almost any of the other groups. It. 
will thus be seen that the study of the Entomostraca, like 
so many of the other departments of nature, has its own diffi- 
culties and interesting problems, for the elucidation of which 
patient workers in larger numbers are needed. 
In bringing these investigations to a close, we desire to 
emphasise the benefits to be derived from a continuous examina- 
tion of a particular loch or pond. When such an examination 
is carried on throughout a whole year, or longer, not only 
seasonal variations may be noted, but the various phases in 
the life-history of a minute plant or animal come under one’s 
observation, the cycle of growth and development is usually 
completed, and a more or less intelligent conception is gained 
of the various complex stages through which many, if not 
most, of these lowly organisms pass. That there must be a 
material gain in such a mode of procedure is evident. Patient 
observation of the processes of nature, as these go on silently 
around us, has its valuable uses, not to speak of its fascina- 
tions. In such a humble task as the repeated examination of 
even a hill-tarn, lessons can be learnt which may help to 
unlock some secret of nature never yet yielded up. 
