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among the mollusca.” Nor do we think that a classification based solely 
on any particular organ can be a sound one. Nevertheless^ Mr. Hogg has 
done good service in developing Dr. J. E, Gray’s view, and the illustra- 
tions which accompany his memoir are both numerous and excellent. 
The Sexual Reproduction of Infusoria. — Dr. Ernst Eberhard’s excellent 
paper on this subject, in the Zeitschrift fur ivissmschaftliche Zoologkj has 
been partly reproduced in the Quart. Jour. Miai'o. ScieneOj for July. The 
abstract is comprehensive and interesting. Dr. Eberhard confirms some of 
Stein’s observations, but has failed to convince himself of the accuracy of 
others. Having very carefully watched a number of Bursaria truncatella, he 
found that they became filled with a number of uniform globular particles — 
indeed, some of them seemed mere saccules of these bodies. Soon, however, 
he saw that these bodies were protruded through the still open slit in the 
parent body,” but they remained attached to its outer surface. After the 
parent had been disintegrated the globular bodies, now at liberty, developed 
a contractile vesicle and spherical nucleus, and presented an acineta-like form, 
whilst short tentacles, with transparent nodular extremities, sprung up 
irregularly all over the surface.” Shortly, cilia presented themselves on the 
surface. In fact, as Dr. Eberhard observes, here was an acinetaform 
which is at some time one of the Ciliata. In this case the embryos all 
originated in the nucleus of the parent. ‘Ht would seem,” says the writer of 
the abstract, that the points at which the author is at issue with Stein are : 
(1) That while the latter observer insists upon the presence of a nucleus 
in all the individuals filled with embryos, the author denies its existence ; 
(2) Stein positively denies the occurrence of the acinetaform progeny, 
whilst the author asserts it j (3) Stein places the contractile vesicle in the 
hinder part of the embryo ] Dr. Eberhard says it is placed anteriorly.” 
