ON THE PILOBOLID.ZE. 
153 
to pressure, the septum at the base will soonest yield, thus 
forcing the contents into the stem ; nay more, the stem can 
often be ruptured and the contents forced into the surrounding 
water, before the sporange itself will yield or burst at any 
part. But when the sporange is mature all this is altered. 
(To be continued .) 
MB. HERBEBT SPENCER’S BIRTHDAY. 
At the request of the Sociological Section of the Birming¬ 
ham Natural History and Microscopical Society we have 
much pleasure in publishing the following correspondence :— 
Wood House, Handsworth Wood, 
Near Birmingham, 
26fcli April, 1884. 
My dear Sir, 
As President of the Sociological Section of the 
Birmingham Natural History and Microscopical Society, I 
have been requested on behalf of the Section to convey to you 
their cordial congratulations on the occasion of your sixty- 
fourtli Birthday, to-morrow, the 27tli instant. 
In the course of a connected and diligent examination of 
your great and original system of synthetic philosophy by 
the members, extending over a period of twelve months, 
they have repeatedly been impressed, not only with the 
vastness of the subject itself, but also with the masterly and 
comprehensive manner in which you have treated it, and 
with the rich and varied extent of your knowledge and 
ability in expounding the all-embracing doctrine of Evolution 
which it unfolds. 
The members of the Section unanimously desire me to 
record their sincere appreciation of the pleasure which the 
study of your works has afforded them, and they desire me 
to express the earnest hope that you may be enabled, not 
only to complete the system which has been the chief work 
of your life, but also to see its general acceptance in after 
years. 
It may be interesting to mention that one of the members 
of the Section, Mr. F. Howard Collins, has presented to the 
Society, as a souvenir of your Birthday, a recent photograph 
of yourself, suitably framed, to be suspended m the Library. 
I am, my dear Sir, 
Yours very truly, 
w. r/hughes. 
Herbert Spencer, Esq. 
