ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
245 
the apparatus is in running order the eggs are placed in the bell-jar and 
spread upon the cloth in a single layer. The short end of the siphon 
is placed in the trough in such a position that when the water is siphoned 
off, the eggs will not be left out of water. The apparatus so works that 
Fig. 40. 
the water alternately rises and falls, washing the eggs constantly in a 
gentle way, but not heaping them together, nor disturbing them to any 
considerable extent. The water that is siphoned from the first trough 
falls into another smaller trough, supplied with jar and eggs, and placed 
far enough below the first trough to prevent interference with the 
siphoning. 
Rodet, A. — Sur la sterilisation du lait. (On the Sterilization of Milk.) 
Rev. d’ Hygiene et de Police Sanitaire , XVI. p. 1025. 
(2) Preparing- Objects. 
Preparation of Fish Embryos.* — Mr. A. T. Holbrook points out 
that Henneguy’s method of treating eggs with Muller’s fluid has the 
objection that the yolk is dissolved out in such a manner as to be sub- 
sequently precipitated around the eggs, which are thus left imbedded in 
the precipitated mass. This difficulty may be overcome by cutting the 
egg-membrane in such a way as to catch an air-bubble within the egg- 
shell, and thus to float the egg in the fluid. The author reports that his 
best results were secured with material killed in picro-sulphuric acid. 
The embryos were left for three hours in the fluid, and then removed 
and dehydrated by passing them slowly through successively stronger 
[ grades of alcohol. In staining, the eggs were passed through weaker 
} grades of alcohol and then stained for 24 hours in Czokor’s cochi- 
i neal. Mr. Holbrook found it best to cut his eggs without attempting 
to remove the membrane or any of the hardened yolk. Great difficulty 
| was experienced in making sections, as parts of the yolk break up and 
fall out of the section, often carrying the embryo with them, while the 
firm membrane is apt to resist the knife, and fold or break the embryo. 
It was found to be a good plan to have a generous amount of imbedding 
[ substance about the object and to cause the knife to strike the embryo 
1 before the yolk, as there is thus less danger that the embryo will be 
turned or pushed by the resisting yolk. 
* Bull. Mus. Comp. Zool., xxv. (1894) pp. 82 and 3. 
