636 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Life-History of Gononemus.* — Mr. L. Murbach lias a preliminary 
note on the life-history of this jellyfish, which occurs in large numbers 
at Woods Holl during July and August. Nothing seems to have been 
done in advancing our knowledge of this form since it was discovered by 
Prof. Agassiz in 1862. The largest specimens taken were 3 cm. in 
diameter and had sixty-four tentacles. The eggs are spherical, granular 
bodies of a light brown colour, the nucleus is large, and no egg-membrane 
could be demonstrated in the eggs until some time after fertilisation. 
Segmentation begins about 1J hours after the deposition of the eggs. It 
is total and equal, especially in the earlier stages ; later on, it is not so 
regular. The cells become columnar, and are arranged around a small 
cavity, giving rise to a blastula. This becomes ciliated, and rotates in 
the egg-membrane. Soon it becomes a pear-shaped free-swimming 
planula. It may persist in this stage for several days or for only forty 
hours, then it elongates, loses its cilia, and becomes attached by the 
end which corresponds to the larger end of the planula. This jellyfish, 
therefore, passes through a hydrula stage, and there appears to be true 
alternation of generation. 
Oogenesis in Tubularia.f — Herr F. J. Th. Doflein finds that the 
ovum of Tubularia larynx is formed by the coalescence of a number of 
germ-cells. The nucleus of the strongest cell dominates over the others, 
retains its individuality, and becomes the germinal vesicle. As to the 
other nuclei, they degenerate, often exhibit amitotic division, but die 
and are assimilated. The plasma of the various coalescent cells becomes 
the plasma of the ovum, and before cleavage begins the ovum is strictly 
a single cell. The resemblance to the oogenesis of Hydra is obvious. 
Porifera. 
Diplodal Sponge-Chambers.i — Prof. F. E. Schulze observed, in 1877, 
that the flagellate chambers of Oscarella lobularis and some other 
sponges had afferent as well as efferent ducts, prosodi as well as aphodi. 
In 1888 Sollas corroborated this, and called such chambers diplodal. 
Lendenfeld, too, while acknowledging the difficulty of demonstrating 
the ducts which connect the inhalent canal system and the chambers, 
did not seem to doubt their existence. Recently, however, Topsent, in 
his monograph of French sponges (1895), has absolutely denied the 
occurrence of diplodal chambers. 
In answer, Prof. Schulze has reinvestigated Corticium candelabrum 
O. Schmidt, Chondrilla nucula O. Schmidt, and Oscarella lobularis, and 
confirms his previous results. The chambers have an entrant and an 
exit aperture ; they are diplodal. Three microphotographs accom- 
panying the paper show this clearly. 
Northern Calcispongise.§ — Herr L. Breitfuss gives an account of a 
collection of Calcispongiae obtained, in 1889, during the Bremer Expe- 
dition (Kiikenthal and Walter) to East Spitzbergen. He describes five 
new species — Lcuccsolenia Nanseni, Sycetta ascono ’des, Ebnerella Schulzei , 
Eh. KuTcenthali, and Pericharax Polejaevi. 
* Journ. Morphol., xi. (1895) pp. 493-6. 
f Zeitschr. f. wiss. Zool., lxii. (1896) pp. 61-73 (1 pi.). 
X SB. K. Preuss. Akad., 1896, pp. 891-7 (1 pi.). 
§ Zool. Anzeig., xis. (1896) pp. 426-32. 
