ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
483 
first sight looks like a dark-coloured fan-shaped Gorgonid. In general 
appearance it is not unlike Dehitella and Ceratella, but these have the 
skeleton in the form of a horny network. 
As the reproductive apparatus is as yet unknown, there is very con- 
siderable difficulty in speaking as to the affinities of the form ; the 
gastrozooids call to mind Clava , the dactylozooids the Plumulariidse, 
and the relationship of the gastrozooids to the coenosarcal tubes the 
Hydrocorallinse. The skeleton, though somewhat resembling that of 
the Hydractiniidse and Ceratellidae, differs by the presence of hydrothecse 
and the possession of a thin layer of external perisarc, with projecting 
cylindrical tubes. The first of these differ in various points from those 
of any other Hydroid, and the second does not appear to be present in 
any other known form, and it is difficult to conceive how it arose. 
Trembley’s Experiments with Hydra.* — Dr. M. Nussbaum has 
repeated his observations on the behaviour of Hydra when turned inside 
out. He corroborates his previous conclusion that a Hydra thus treated 
and bored by a needle, recovers its normal arrangement of ectoderm and 
endoderm by a process of overgrowth and turning outside in, which may 
take effect at various places, and is associated with complex absorptive 
and formative changes. Some new details are added ; thus, it is noted 
that a Hydra turned inside out may live in this state, at the expense of 
its own substance, for six days. Much of the paper has to do with an 
unfortunate discussion which has arisen in regard to the contributions 
which Nussbaum and Ischikawa have made to the solution of the problem 
of the restitution of an evaginated Hydra. 
Protozoa. 
Intracellular Digestion in Protozoa. - ]* — M. Le Dantec has made 
experiments on intracellular digestion, following the same line as 
Metschnikoff, who showed that the chemical reaction of the contents of 
the vacuoles is acid, while that of the protoplasm is alkaline. The 
author used Stentor polymorphus and other Ciliata, and tested the vacuolar 
reaction with litmus grains. The secretion of the acid varied as to 
rapidity with the species examined, but in all cases appeared to be the 
same in kind. 
Better results appear to have been obtained by using a sulphur com- 
pound of alizarin (alizarine sulfoconjuguee). This is a brown pigment 
soluble in water (1-500) which when acted upon by alkalies becomes 
violet and yellow by acids. The transition stage being pink, the slightest 
alteration in the reaction is instantly recognizable. 
With this pigment two kinds of amoebae were experimented on. A 
few minutes after the inception of the pigment- granules an acid re- 
action was observable within the vacuoles, for the contents, originally 
violet, changed to pink and sometimes to yellow. The pigment-granules 
were afterwards frequently eliminated, retaining the colour they had 
acquired while within the vacuole. 
He finds that J in all cases the solid particles taken in were accom- 
* Arch. f. Mikr. Anat., xxxvii. (1891) pp. 513-68 (5 pis. and 1 fig). 
f Annales de l’lnstitut Pasteur, 1890, pp. 776. See Centralbl. f. Bakteriol. u. 
Parasitenk., ix. (1891) pp. 355-6. 
X Ann. Inst. Pasteur, 1891, p. 163. See Centralbl. f. Bakteriol. u. Parasitenk., ix. 
(1891) p. 736. 
