44 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
no common orifice, as in the Anatinacea among Lamellibranchs, and in 
Entoconcha among Gastropods. These last exhibit the highest specializa- 
tion of the hermaphrodite state. Whatever, however, be the extent of 
the hermaphroditism of a Mollusc, the eggs of one individual have to be 
fertilized by the spermatozoa of another ; as in the hermaphrodites of 
other groups, protandry is general. 
The author proceeds to show that hermaphroditism is not a primitive 
arrangement in the Molluscan phylum, and that it has been derived from 
the unisexual stage ; and further, that it has become superimposed 
upon the female condition. Fixation, parasitism, and fluviatile or terres- 
trial habitats appear to be specializations accompanied by hermaphro- 
ditism ; of them the Oyster, Entoconcha , the Pulmonate Molluscs, and 
the Oligochaete Annulata are, respectively, examples. 
What is true as to the appearance of hermaphroditism after the 
separation of the sexes in Mollusca is true also of Myzostomidae, Crus- 
tacea, and Fishes, as well as of plants ; and in Crustacea and Fishes, at 
least, hermaphroditism is grafted on the female sex. 
y, Gastropoda. 
Pedal Gland of Pulmonata.* — M. E. Andre has examined this gland 
in a number of forms, and applies the terms “ superior masses ” to the 
glandular masses which are found in its supero-anterior part. The floor 
of the excurrent canal is ciliated, and has intercellular passages. In 
addition to the just-mentioned masses the glandular part contains ordi- 
nary and vacuolated glandular cells. The first, which are formed from 
connective-cells, form in their interior secretory products which they 
expel into the intercellular passages, and thence into the canal. After 
excretion the cell is for a period in repose, again elaborates secretory 
products, and eliminates as before. After repeating this several times 
the cell dies and is expelled. 
The gland is not a sensory organ, but has to secrete a lubricating 
mucus on the path taken by its possessor ; this mucus is driven out by 
the cilia, by vis a ter go, by compression of the gland by muscular bundles, 
by the undulatory movements of the foot during progression, and by the 
movements of the whole body. Blood cannot pass out by the gland, but 
a fluid from the exterior may traverse the intercellular passages. 
Anatomy of Trophon.j — Dr. L. Plate has a note on the enteric 
canal and kidney of what is probably Trojohon geversianus. The pharynx 
is small, and the radular papilla is a long thin filament, 8 mm. wide, 
The kidney corresponds in position and structure with the description 
given by Bemy Perrier in his work on the Muricidae, but Dr. Plate 
cannot accept his explanation of the nature of the high fold found in it. 
Origin of Mesoderm in Paludina.J — Dr. R. v. Erlanger has revised 
his account of the origin of the mesoderm in Paludina vivipara, on 
which Korschelt has cast doubt. He corroborates himself : — Paludina 
is certainly enterocoelic, but besides a coelom sac there are primitive 
mesoblasts ( [Urmesodermzellen ). These are the forerunners of those 
* Rev. Suisse Zool., ii. (1894) pp. 291-348 (2 pis.). 
t SB. Ak. Wiss. Berlin, 1894, pp. 224 and 5. 
X Morphol. Jahrb., xxii. (1894) pp. 113-8 (1 pi.). 
