1. Attempts to obtain good cultures of Thalassiosira gravida in a purely artificial medium, made by dissolving in doubly distilled water Kahlbaum's pure chemicals in the proportions in which the salts occur in sea-water, adding nitrates, phosphates and iron according to Miquel's method and sterilizing the medium, have not succeeded.

If, however, a small percentage of natural sea-water (less than 1 per cent will produce a result) be added to the artificial medium and the whole sterilized excellent cultures are obtained, which are often better than any which have been got when natural sea-water forms the foundation of the culture medium.

The result appears to be due to some specific substance present in minute quantity in the natural sea-water which is essential to the vigorous growth of the diatoms. The nature of this substance it has not been possible to determine, but some evidence seems to suggest that it is a somewhat stable organic compound.

Provided the 1 per cent of natural sea-water is added, the various constituents of the artificial sea-water forming the basis of the culture medium can be varied in amount within wide limits. The salinity of the medium can also be considerably altered without serious detriment to the cultures.

The experiments recorded are of interest as furnishing another instance of the importance in food substances of minute traces of particular chemical compounds. They may also eventually throw light upon the nature of the conditions in the sea which are specially favourable to the production of plant life and therefore also of the animal life which that plant life sustains.

The Hydroids experimented on were Antennularia ramosa, and A. antennina.

These were cut in pieces and pressed through bolting silk, with the result that isolated cells and small cell aggregates were obtained, which soon aggregated together to form compact masses.

These restitution masses secreted a perisarc within from 12 to 18 hours.

Various changes in shape, and general retraction of the mass away from the perisarc occurred later, but even up to 60 days there was no sign of the regeneration of the hydranths.

The restitution masses consisted of ectoderm and endoderm cells, and in addition such structures as nematocysts, ova, and brokendown cells, all of which were subsequently absorbed and played no part in the future development. The ectoderm cells were relatively little damaged, and were embedded in a plasmodial mass formed by the endoderm cells.

A definite layer of ectoderm cells is formed on the surface, and thesecells secrete the perisarc.

Gradual aggregation and segregation of the endoderm cells from the plasmodial mass takes place ; and they form very definite tubules similar in structure to the coenosarcal tubules continuous with the enteric cavities of the normal hydranths. These tubules are embedded in a mass of ectoderm cells, they are convoluted and ramify in all directions. Many granules develop in the cytoplasm of these cells, and after about a month many of them have degenerated.

The ectodermal cells show no signs of degeneration, and the masses containing them have been kept alive for 60 days at the time of writing.

In none of the experiments was there any sign of the occurrence ofcell division

An investigation on inheritance in hybrids between the three English species of Echinus was carried out in the Marine Biological Laboratory, Plymouth, during 1909–1912 by C. Shearer, W. de Morgan, and H. M. Fuchs. In a paper published in the Phil. Trans. Royal Soo., Ser. B, Vol. CCIV., p. 255, the results of this work were described in detail. At the time of publication, E. miliaris had been raised from the egg to maturity in the laboratory, in the course of one year, and a second generation had been obtained from these individuals, but none of the hybrid urchins had as yet reached maturity. This year, however, some of the hybrids have become sexually mature, and from them a second hybrid generation has been raised.

The urchins which have formed ripe genital products are four individuals of the cross E. esculentus X E. acutus (referred to below as EA) derived from fertilizations made in 1912. The largest of these urchins now measures 6 cm. in diameter, exclusive of the spines. On May 11th, 1914, two of these hybrids laid eggs in the tank in which they were kept. Naturally these eggs could not be used for experimental purposes, since they were deposited in the sea water of the aquarium circulation, and therefore not under sterile conditions. On June 6th I induced three of the four to deposit genital products without cutting them open, under conditions which excluded the possible presence of foreign eggs or spermatozoa. It is hardly necessary to mention here that, as in all the previous work on Echinus hybrids, the fact of the complete absence of such sperm was made certain by controls of unfertilized eggs, none of which segmented.

In continuation of my researches on the entozoa of British marine fishes I spent two months (August and September, 1909) at the Plymouth Marine Biological Station. By the courtesy of the Government Grant Committee of the Royal Society, a table was placed at my disposal and all expenses in connection with the investigation were defrayed.

A hermaphrodite specimen of Amphioxus has been taken at Plymouth having one gonadial pouch filled with ova and the remaining pouches filled with sperm. This specimen closely resembles a similar one taken by Goodrich at Naples.

The liver and intestine of the Plymouth specimen are abnormal, but no parasites have been identified in the tissues to account for these abnormalities.

It is, moreover, improbable that there is any normal sex-change in Amphioxus, since three independent investigators have found very small specimens of both sexes, therefore no satisfactory explanation can be given of the occurrence of hermaphroditism in the specimen.

Amphioxus have been found to spawn in June, and larvae have beenobtained from the captive specimens.It is suggested that the club-shaped gland may secrete a substance for attaching the larva of Amphioxus to objects, and that this function may be correlated with the asymmetry shown in the early development of the Amphioxus .larva.