ANNELID BIONOMICS. 947 
history. Do Enchytreids moult, or is there ever a marked 
difference between the young and the adult ? I put this question 
in one or two scientific papers, but have never seen any attempt 
at an answer. So far as my own researches, extending over 
two decades, are a guide, I find that there are often very striking 
differences between young and adult, but nothing which can be 
described as a larval condition or a moulting process. 
That being the case, one had to look for another explanation 
of the fact. When some time later I received the same forms 
from Ireland under similar conditions, the explanation seemed 
clearly to be found in assuming that one form acts as the 
pioneer, and another appears upon the scene when the stage of 
decay has somewhat more fully advanced. 
This theory, which is perfectly in harmony with what we 
know to be the case in other departments of life, has just 
received such striking confirmation that I hope to be able to 
accumulate facts for its confirmation or refutation. In August, 
1911, I spent some time, through the courtesy of Mr. Robert 
Gurney, in his laboratory on Sutton Broad. The débris on the 
shores was carefully studied, and a full list made of the different 
species of Enchytreids which were then engaged in breaking up 
the vegetable débris. On leaving the laboratory I collected 
(August 25th, 1911) a quantity of the débris, and kept it for 
further study. In this gleaning were a number of the Enchy- 
treids which I had tabulated, and they carried on their work 
during the winter. As the summer came on, however, and the 
work of the annelids progressed, I found the material contained 
new species of white worms, such as were nowhere to be found 
in the previous autumn. Their eggs had clearly been deposited 
in the locality, and the parents had disappeared. LHventually 
the cocoons had ripened, and the worms emerged to take up the 
work at the stage to which the other species had brought it. 
Some twenty years ago I worked, one February, along the 
banks of the Eden near Carlisle, and found some tiny Fride- 
ricias at work among the decaying vegetable matter. I now 
find that these species may be successfully looked for at this 
time of the year, whereas they will be sought in vain in such 
localities at other seasons. Evidently they have their particular 
mission, a mission which must be discharged at the time when 
