550 Records of the Indian Museum. [Vo.. XI, 
The great numbers of developing nettling organs in this region 
clearly indicate it as a localised manufacturing area whence migra- 
tion of fully developed nematocysts to the tentacles takes place, 
conditions apparently of general occurrence in the Hydromedusae 
(see Hadzi, I9Ir). 
The mesogloea is colourless and of almost uniform thinness 
of 2p. 
Endoderm.—The endoderm cells present more variety in their 
shape and in their inclusions than the ectoderm. Asin many other 
hydroids they fall into three indefinitely bounded regions, in all of 
which, however, a few longitudinal ridges of elongated cells project 
into the coelenteron. 
The hypostome endoderm consists of a series of regular, 
elongated, narrow, palisade cells resting upon the mesogloea and 
lacking inclusions. Between the distal ends of these cells are 
inserted many clavate gland cells, with a large nucleus resting in 
the wedged-in narrowing portion of the club, and a content of 
finely granular cytoplasm. 
In the region of the tentacle-zone the endoderm is consider- 
ably deeper. The palisade layer of the hypostome is replaced 
by several irregular rows of small highly-vacuolar cells. Upon 
these rest large clavate nutritive cells, containing oval nuclei and 
coarsely-granular secretory products, as well as foreign bodies the 
recognisable portions of which consist mainly of the frustules of 
diatoms. Throughout the endoderm in this region there are scat- 
tered dark oval cells containing excretory products. 
Lastly in the prolonged basal portion of the hydranth the 
cell-varieties of the former regions disappear, and the endoderm 
consists of a network of regular, highly vacuolar cells in which the 
cytoplasm and nuclei are ranged along the cell-walls. Here the 
cells are almost devoid of inclusions, only a rare individual with 
excretory products being observable; and although a narrow central 
lumen penetrates the region it is clear that the cells lining it take 
little part in the secretory or digestive functions. 
The structure of the basal bulb will be discussed in the section 
dealing with reproduction (p. 553). 
METHODS OF REPRODUCTION. 
I. SEXUAL REPRODUCTION. 
There is no conclusive evidence of the occurrence of a sexual 
type of reproduction in the specimens which I have examined, 
although in one there is present, arising from the tentacle-zone, a 
very small globular bud (0°045 mm. in diameter) composed of 
ectodermal and endodermal elements, which might possibly have 
developed into a sporosac or medusoid gonophore. Its position 
within the tentacle-zone agrees with the position rather of the 
sexual bodies than of the simple buds of most other hydroid 
species. 
