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On the Development of Tuhularia indivisa. By J. B. Mum- 
mery, Esq. [Read May 26, 1852.] 
Having found considerable difficulty in reconciling the accounts 
given by various naturalists of the development of Tuhularia 
indivisa, I was gratified to have discovered a locality whence I 
could obtain by the dredge a regular supply of fresh speci- 
mens of that very interesting zoophyte ; and during the past 
six months have made almost daily observations by the micro- 
scope upon its structure and development. 
The painstaking investigations of the late Sir John Graham 
Dalyell appear to have supplied much of the information pub- 
lished on the subject. 
It appeared however to me, on comparing the results of my 
own observations with the accounts and figures contained in 
the work of that indefatigable observer, that he had ever 
laboured under the disadvantage of employing a very imperfect 
microscope, and consequently misapprehended some of the 
phenomena to which he directed his patient attention. 
The general form of Tuhularia indivisa has repeatedly been 
well described, but there are some portions of its structure re- 
specting which greater accuracy appears desirable. The repro- 
ductive gemmules have usually been described as originating at 
the base of the lower row of tentacules, and, owing to the pro- 
fusely crowded situation of these oviform bodies in the full- 
grown head, it is quite impossible to detect their real place of 
attachment to the body. It is however a well-known fact, 
that the full-grown head within three or four days drops from 
the stalk, and that in the course of six or seven days a new head 
is produced from the medullary pulp. On examining the 
newly-formed head, under a magnifying power of fifty diame- 
ters, the oviform gemmules are even at this early stage per- 
ceptible, arranged upon the outer surface of the body, and ex- 
tending vertically from the lower tentacules to the base of the 
oval tentacules in twelve equidistant lines ; two of the lower 
tentacules originating in the space between each ovary, thus 
making the whole number twenty-four. 
In the early stages of their growth the capsules are attached 
to the ovary by a very short and somewhat thick stalk ; the 
stalk gradually becomes elongated, having the capsules affixed 
alternately on each side throughout its length by a broad attach- 
ment, and the substance of the capsule is now of a pale rose- 
colour. 
As development advances the general rosy tint disappears, 
and the colouring matter appears concentrated in a well-defined 
organ of deep-red colour, which evidently supplies the connect- 
