586 Muller's Archivfur Anatomic, fyc. 
Salices, &c. In a valley surrounded on all sides by mountains, from which the 
Narzanza takes its rise, and where there are thermal baths resorted to by invalids^ 
the most conspicuous and interesting plants are the following : Betonica grandi- 
flora, Polygala Sibirica (Linn.), Rhinanthus orientalis, (Linn.), Primula amoena, 
Dianthusfragrans,Azaliapontica, (Linn.), Trollius Caucasicus, fyc. Beseh- 
reibung einiger neuen in Liefland augefunden insecten, Von B. A. GIMMER- 
THAL. Contains descriptions of several new dipterous and neuropterous insects. 
Muller's Archiv Jur Anatomic, Physiologic, Sfc. Parts iii. and iv. 
1836. (Continued from p. 292.) 
Ueber de Metamorphosen des Eies der Fische u. s. w- Von M. RUSCONI. 
On the changes which the Ova of Fishes undergo previous to the exclusion of the 
Embryo. In order to continue his observations on this subject, the author re- 
paired to the lake of Como early in July, being assured by the fishermen that 
both Tench and Bleak deposit their spawn at that period. On the 10th of that 
month he procured some eggs from a female tench (Cyprinus tinea, Lin.), and 
placed them in a glazed earthenware vessel filled with water from the lake. 
They immediately sunk to the bottom, and two or three drops of milt were ex- 
pressed from a male fish upon them. The eggs were perfectly transparent, and 
of a greenish yellow colour, like that of olive oil. The milt was of the colour 
of milk, but much less fluid. In four hours after the fecundation, some of the 
eggs seemed to have lost their transparency on one side, and others by degrees 
assumed the same appearance, so that in twenty-four hours they had all become 
opaque, and their vitality was considered to be extinct. This the author sup- 
posed to have arisen from too large a quantity having been laid one upon another 
in the vessel, and he accordingly took a flat shallow dish, the bottom of which 
was covered with paper, and filled it with lake water. Some more fecundated 
ova were then placed in it, so that they did not come in contact with one ano- 
ther. In five hours he again remarked that some had become opaque on one 
side, and in twenty-four hours the same thing had occurred to nearly all. Some 
few, however, remained transparent, and these he rais-ed gently from the dish, 
by means of the paper that was under them, and transferred them to glasses of 
water for farther observation, placing eight or ten in each ; in six or seven hours 
after this operation, he saw by means of a microscope that the embryo had be- 
gun to move, and in twenty -four hours (fifty from the moment of fecundation) 
the young fishes burst through their envelope. The experiment was again re- 
peated in order to ascertain whether the ova of fishes undergo similar changes 
to those of the Batrachians (vide Analysis of Muller's Archiv at p. 292,) 
and half an hour after the eggs had been placed in the dish, he lifted out those 
which remained transparent, and transferred them to glasses as before. It was 
now his object to destroy the vitality of some of them at each stage of their de- 
velopment, in order to examine the progress that had been made, at leisure, and 
for this purpose he dropped into the water four or five drops of a mixture of 
one part of nitric acid and eight parts of water, which had the desired effect. 
This was applied at intervals of fifteen minutes during ten hours, and the follow- 
ing are the results obtained : Soon after the application of the milt, the ovum of 
the tench loses its spherical form, and swells out into the form of a pear. At the 
