490 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
infested snails. Eggs of the parasite were found in the faeces of the 
hedgehog seventeen days after feeding, and after about a month both 
hedgehogs died of intestinal inflammation induced by the swarms of 
parasites in the intestine. The sexually mature Distomum agrees in 
most respects with the cercaria, save for an elongation of the budy and 
the modifications produced by the presence of the ripe gonads. The 
spinose cercariae produce a spinose adult forming the species Distomum 
spinulosum. In order to complete the cycle of observations, snails were 
fed on leaves sprinkled with Distomum eggs, and the eggs themselves 
were cultivated in extract of snail’s stomach. The feeding experiments 
did not yield absolutely satisfactory results, but the cultures showed 
that the eggs hatch at once in the digestive fluid of the snail without 
previous immersion in water. The free miracidium finds its way to 
the interstitial connective tissue and becomes a vesicular sporocyst, 
which later grows out into a much branched tube containing swarms 
of cercariae. 
Regeneration in Planaria.* — Prof. T. H. Morgan has made 
numerous experiments with Planaria maculata. Some of the results 
may be briefly noted. Transversely cut portions may grow a new 
“ head ” and “ tail.” The pharynx may be re-formed in different ways 
according to the position of the cut. The transversely cut portions 
decrease in breadth and increase in length. If the foremost portion 
in front of the eyes be cut off, it does not regenerate an entire worm, 
as is the case if the cut pass just behind the eyes. As even smaller 
portions than that in front of the eyes may re-grow a whole, the absence 
of regenerative capacity in the most anterior portion cannot be accounted 
for by the small size, but perhaps by the greater specialisation. In 
most cases the regeneration shows a distinct polarity, but there is great 
diversity of results, thus a head may be formed at each end. The author 
compares the material of this marvellously plastic body to that of a 
segmenting ovum. 
Gyrodactylus in Salt Water. f — Prof. L. Kathariner records the 
occurrence of G. medius in Motella communis from Heligoland, and in 
species of Cyprinodon from warm mineral water in the Sahara. A few 
cases of its occurrence in marine fishes have been previously noted. 
As its usual habitat is on fresh- water fishes, its power of acclimatisation 
must be great. 
Incertse Sedis. 
Rhabdite-“ cells ” in Cephalodiscus..]; — Mr. F. J. Cole, in the course 
of an investigation of some fragments of Cephalodiscus, has discovered 
some remarkable structures in the branchial plumes. As is well known, 
these terminate in bulbous enlargements regarded by Masterman as 
eyes. When stained with Dr. Mann’s methyl-blue-eosin, it is found 
that these bulbs are covered by “ cells ” containing rhabdites in all 
respects similar to those of Turbellarians or Nemerteans. The wall 
of the bulb consists of (1) a series of large nucleated basal cells, and 
(2) a series of non-nucleated bodies placed in vacuoles and termed 
* Arch. Entwickmech., vii. (1898) pp. 364-97 (41 figs.). See Zool. Centralbl., vi. 
(1899) pp. 560-2. t Zool. Anzeig., xxii. (1899) pp. 328-9. 
X Journ. Linn. Soc. (Zool.), xxvii. (1899) pp. 256-68 (1 pi.). 
