Dae G. CARL HUBER 
the observations made on sections, as will be discussed later. 
By cutting the oviduct at about its middle, freeing it from its 
mesosalpinx and cutting the uterus about 1 em. below the in- 
sertion of the oviduct, a pipette fitted with a rubber bulb and 
filled with warm normal salt solution can be inserted into the 
uterine cavity and moderate pressure made. It is usually possible 
to wash into a watch crystal a certain number of the contained 
segmenting ova. Before reading the article by Widakowich, 
essentially the same method as employed by him, for isolating 
implanted blastodermic vesicles was developed. This may be 
quite readily done after fixation in Carnoy’s fluid and teasing 
under a_ stereoscopic binocular. Vesicles sectioned in situ, 
however, gave on the whole more satisfactory results, so that 
teasing out implanted vesicles was not resorted to. 
The fixed tissues were imbedded in paraffin, using xylol as 
a Clearing fluid. For stages including those falling within the 
period ranging from the first to the fourth day after insemination, 
the ovary and oviduct to its insertion in the uterus, were em- 
bedded en masse. For stages falling within the period of fifth 
to sixth day after insemination, the uterine horns were divided 
into segments measuring about 1.5 cm., and sectioned parallel 
to the plane of the mesometrium. For later stages, after the 
enlargements in the uterine horns are distinctly evident, these 
were removed and cut severally in the three planes. The great 
majority of the sections were cut at a thickness of 10 uw; certain ones 
ata thickness of 5 u; afew at athickness of 7u. The sections were 
fixed to the slide by the water-albumen method. The great ma- 
jority of the series were stained in hemalum, counterstained in 
Congo red. This solution, which presents certain advantages as a 
counterstain for embryologic tissues, is prepared as follows: 0.5 
ems. of Congo red (Gribler) is placed in 100 cem. of distilled 
water and the water brought to boiling. This should give a clear 
solution. Before cooling, add 100 cem. of distilled water and 
10 cem. of absolute alcohol. The Congo red solution thus pre- 
pared may be kept many weeks. After staining the series in the 
usual way in hemalum, they are differentiated in acid alcohol, 
and passed through several washes of ‘tap water’ into distilled 
