460 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
possible, to discover something as to the distribution and possibilities of 
embryonic tissue. 
The whole stem and the hydranth may be reproduced after a cut 
through the stalk at any of the levels. A few rings only and the 
hydranth may be reproduced after a cut through the stalk at any of the 
levels. The nearer the cut to the proximal end, the greater the per- 
centage of cases of reproduction of an entire stalk (with unsegmented 
tract). The nearer the cut to the distal end, the greater the definiteness 
of regeneration, the less the mean number of rings regenerated, and the 
smaller both the upper and lower limit in the number of rings regene- 
rated. Such are some of his concrete results. 
More generally, Davenport concludes that the regenerative tissue is 
not differentiated at different levels to produce different things, indepen- 
dent of environment ; but on the contrary the embryonic tissue at all 
levels may produce the same things. Wholly aside from the necessary 
production of definite things, there may be acquired in certain embry- 
onic tissues a usual method of development, independent of environment. 
The definiteness is a function of the distance of the cut edge from the 
base of the stem, and, in more general terms, of the natural frequency of 
a demand for regeneration. The curves of regeneration show no im- 
portant indication of difference in the germ-plasma at different levels in 
respect to the size or form of the parts which regenerate ; but there is 
a tendency of the regenerative tissue at all levels to produce preferably 
certain forms. 
Limnocnida tanganyicse.* — Mr. E. T. Gunther, in his second paper 
on this African freshwater Medusa, gives the results of his more minute 
examination of the material at his disposal. We known so little of the 
life-history of the form that it is impossible to say with certainty 
whether or no it is one of the Narcomedusse ; it is suggested that the 
striking similarity of the sense-organs in it and Limnocodium is the result 
of homoplasy. 
A list is given of freshwater Coelentera, and it is pointed out that 
there is no reason for doubting that they are all descended from marine 
ancestors ; with regard to Lake Tanganyika, in which Limnocnida is 
found, it has been shown by Mr. Edgar Smith that it is associated with 
several genera of Mollusca which are perfectly unique in fresh water, 
and which would most certainly be considered to be marine forms, if 
their true habitat was unknown. A suggestion is made as to the origin 
of the marine fauna of this lake, but our knowledge of the geology of 
the country is not sufficient to enable us to be certain of its propriety. 
Lucernaria of Port Erin.f — Mr. W. I. Beaumont, who has been 
working at the Isle of Man station, has found three species of this 
group ; Depastrum cyathiforme is fairly abundant, Raliclystus auricula 
and H. sp. (? n. sp.) are rarer. The first of these, unlike most Lucer- 
naria, appears to be unable to reattach itself if it becomes detached ; 
an account is given of the various names which have been applied to 
this species. It is to be noted that Depastrum, and apparently other 
members of the group, are subject to much variation, especially in the 
* Quart. Jouru. Micr. Sci., xxxvi. (1894) pp. 271-93 (2 pis.). 
t Trans. Liverpool Biol. Soc., vii. (1893) pp. 253-63. 
