206
LEO LEMEË
It is apparent that the increase in erythrocyte number is fairly
constant from the 2nd day (0-11 million) till the 16th day of incubation ;
thereafter the erythrocyte number oscillates around 2-80 million but
does not exceed that of the adult hen, which is about 3-0 million per
cu.mm (Sandreuter, 1951; Lemez, 1953, 1955; Romanoff, 1960; Jaffe,
1960).
2
5
8
11
14
17
20 1
A
Β
AGE OF EMBRYO/DAYS/
FIG. 2. A. Haematocrit values as given by various authors ; B. Erythrocyte number per
cu.mm and haemoglobin content (after Rychter et al., 1955a) from the 2nd day of
incubation to the 1st postembryonic day (A = adult hen). ---Yosphe-Purer et al.,
1953;
, Rychter et al., 1955;
Johnston, 1955; #, Barnes and Jensen, 1959.
The erythrocyte count for duck embryos is given from the 12th day
of incubation by Fetischeva (1939) and for starling embryos is given
from the 9th day by Sandreuter (1951).
The determination of haemoglobin concentration normally requires
larger blood samples. Consequently, data are rarer and start usually
with later developmental stages. Ascarelli (1895) was again the first to
estimate the haemoglobin content ; he started at the 7th day of incubation and continued till hatching. Sümegi (1932) started at day 15, Zorn