155 
section, which will speedily render it transparent. As soon 
as this is the case, the oil of cloves should be removed as far 
as possible, in the same way as the alcohol. A small quantity 
will of course remain behind. A drop of Dammar varnish 
should now be let fall on the section, and a covering glass 
applied, when the preparation will be finished. It is better 
to put a piece of tissue paper, with a hole punched in the 
centre, under the covering-glass. It becomes soaked through 
with varnish, and adheres to the slide and cover. If this 
paper be not used in preparations of early stages, the weight 
of the covering glass is very apt to crush the section, and 
spoil it before the varnish has had time to set. 
By cutting sections of sufficiently advanced embryos at 
right angles to the long axis of the body, very interesting 
preparations illustrative of thedeyelopment of the sense organs 
may be obtained. 
I have ventured to describe these methods at such length 
here, because they are applicable not only to the frog’s egg, 
but also with slight modifications to all the finer histological 
problems, such as the retina, the organ of taste, the Schnei- 
derian membrane, and Corti’s organ. 
A paper in Max Schultze’s ‘ Archiv,’ 1869, erstes heft, 
by Dr. A. Goethe, on the development of Bombinator igneus, 
will be found very useful by those working up the sub- 
ject. The plates are very clear, and there is no difference 
of any moment between this animal’s development and that 
of the frog. Consult also Rathke’s ‘ Entwickelungs-ges- 
chichte der Natter,’ K6énigsberg, 1839; Reichert ‘Das 
Entwicklungsleben im Wirbelthierreich,’ Berlin, 1840 ; 
Remak ‘ Untersuchungen tiber d. Entwickelung der Wirbel- 
thiere,’ Berlin, 1855; ‘ Vogt. Unters. ii. d. Entwickelung der 
Geburtshelferkrote,’ Solothurn., 1842. 
On some INTERESTING Points concerning the Move of 
Repropuction of the Bryozoa. By Dr. Hinricu 
NirscueE, of Leipzig. 
A great many papers on Bryozoa have been published, 
but since the majority of them give mere descriptions of 
the various external forms of the colonies and single cells, 
our knowledge of the anatomy, histology, and mode of re- 
production of these interesting animals is still very limited. 
A great advance as regards the latter point, the reproduc- 
VOL. XI.—NEW SER. L 
