598 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
the liver contains excretory cells with large vacuoles. In Prosobranchs, 
on the other hand, the liver appears to be purely a digestive gland, and 
takes no part in the excretion of injected substances. 
Paired Nephridia of Prosobranchs.* — Dr. R. v. Erlanger was struck 
by the contradictory statements which have been made as to the reni- 
pericardiac duct of various Molluscs. He finds that Trochus , Turbo , 
and Haliotis possess a left reni-pericardiac duct only, while Fissurella , 
Emarginula , Puncturella , Patella , and Tectura possess no such duct. 
The genital products always pass through the right renal organ, either 
by bursting of the gonad through the walls of the right kidney ( Patella 
and Trochus ), or being admitted through a kind of valve (Haliotis), or 
transported to the right renal papilla by a special genital duct ( Fissu- 
rella ). The author concludes that the only remaining kidney in most 
Prosobranchs is the actual left one : that the actual right kidney has 
disappeared or become transformed, part of it forming part of the 
genital apparatus. He is quite convinced that the lamellar kidney of 
Ampullar ia is homologous with the actual left kidney of Paludina, and 
the vascular sac of Ampullaria with the rudimentary right kidney in 
Paludina. The result of a comparative survey is that Dr. v. Erlanger. 
comes to the conclusion that all the evidence tends to show that the 
Mollusca are true Coelomate animals, and that the condition of the 
renal and genital organs is closely similar to that of primitive 
Annelids. 
Colourless Globulin in Patella. t — Dr. A. B. Griffiths gives an account 
of a globulin Irom the blood of the limpet which is colourless and con- 
tains no metal. The author calls it achro[oJglobine, and shows that 
it has a respiratory function. 
Respiratory Value of Haemocyanin to Helix pomatia.t — M. L. 
Cuenot finds that haemocyanin, in the snail, is capable of absorbing 
more oxygen than an equal volume of water, and undergoes changes in 
tint ; its power of absorbing oxygen is, however, very much less than 
that of the haemoglobin of Vertebrates. 
Cerata of Nudibranchs.§ — Prof. W. A. Herdman and Mr. J. A. 
Clubb discuss the innervation of these organs, and show that there are 
various arrangements of nerve-supply. They may be innervated entirely 
by the pleural ganglia, as in Polycera and Ancula, or chiefly by the 
pleural, with a small supply from the pedal by means of a pleuropedal 
anastomosis, as in Dendronotus , or entirely by the pedal ganglia, as in 
Tergipes , or chiefly by the pedal with a small independent accessory 
supply from the pleural, as in Facelina. If the nerve-supply be taken 
as the criterion of homology we are clearly led to an absurd position. 
The fact is that the innervation has probably undergone alteration in 
accordance with changes in the position, size, aud relation to other 
organs of these ceratal processes. It may readily be supposed that, 
when such modifications have taken place as led to the appropria- 
tion of important organs like large blood-sinuses, huge hepatic caeca, 
* Quart, Joyrn. Micr. Sci., xxxiii. (1892) pp. 587-623 (2 pis.). 
f Comptes Reudus, cxv. (1892) p. 259. j Tom. cit., pp. 127-9. 
§■ Quart. Journ. Micr. Sci., xxxiii. (1892) pp. 541-58 (3 pl8.). 
