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Scheel Letters: Resting Embryo
Courtesy of
ARK - Arizona Rivulin Keepers
The Scheel Letters, No. 2
Resting Embryo
When working with very small batches of eggs, in which the number of eggs were
counted and where each egg was inspected under the microscope, and all information
noted on the "card" for each batch, in 1958, I found something that pointed in
the direction of the existence of a state of development which may be called
"Resting Embryo". In these eggs, in the microscope, it was very easy to find
an unpigmented embryo, which also had no blood-system developed. These early
states of the development of the embryo had a distinct segmentation of the long
and slender body and also traces of what later on should be the eyes. The full
length of such embryos was about 180_ that is to say that the whole body occupied
half the circumference of the yolk ball. But these embryos apparently did not
develop further. I thought that they were dead, but as the eggs did not get fungus,
or decomposed inside, I thought that this possibly could be a new type of "dormant
life of eggs". These "apparently dead or sleeping" states of development I first
saw in several batches of eggs of Nothobranchius palmquisti, later in the different
crosses in this genus, but I had not time enough to explore this matter further.
Then my friend Claus Petersen gave me a few eggs of another Nothobranchius, which
he called "kuhntae" (possible "orthonotus" or something like that). These eggs
had been in water (rather dirty to my opinion) for some time, perhaps a month or
so. I got them during the first days of Oct. 58. After some days in water, where
they showed no change, I dried them up in a little peat.
First watering on 09 Nov. 58, no fry hatched. I washed out 11 eggs, 10 of those had that small transparent
embryo, and one egg only had no trace of an embryo. Dried up in the same peat once
more.
Second watering on 12 Dec. 58. No fry. Eggs are unchanged. Dried again on 14
Dec. 58.
Third watering on 16 Feb. 59. Three sound fry hatched (these are now 2
males and one female, typical "kuhntae", the first of these in my fishroom). I
washed out 6 eggs, 5 still were unchanged and had that transparent embryo, no
decomposition of the yolk, egg still transparent. Only one egg did not have this
small embryo or ???. difficult to see.
18 March 59. Fourth watering, no fry,
one" white egg", 5 transparent eggs of which still had the small transparent embryo.
One egg had no embryos. They are now in their peat once more.
Summer 1958 I spawned Nothobranchius melanospilus, from the stock that Jack
mailed me (Henry Hansenstock). Here are the data of one of the batches of
eggs spawned by my young fishes. The egg of that species is much bigger than
eggs of N. guntheri and N. palmquisti and these eggs are easily recognizable
if they should be mixed up with other eggs. I did not find any other eggs in
that peat. Peat out on 17 Jul. 58, eggs concentrated by washing in little and
coarse peat. On shallow water until 02 Aug. 58. Then dried up.
First watering
on 02 Sept. 58, no fry. Second drying up on 14 Sept. 58.
Second watering on 26
Nov. 58, 10 fry, peat washed out and only one egg was found. Not inspected under
microscope (at least not noted on the card of this brood) but it was transparent.
Dried in a little peat alone on 28 Nov. 58.
Third watering on 25 Dec. 58. No
hatching, egg washed out (for which I keep in a separate box, I then place the
eggs in a little amount of peat in a large drop and put lid on. Not all eggs
seem to stand this very quick drying up). Egg inspected under microscope. An
180 degree non-pigmented embryo was seen in egg.
Fourth drying on 30 Dec. 58.
Still fine and transparent, no decomposition of yolk.
Fifth drying on 24 Feb. 59.
Fifth watering on 14 Mar. 59. No fry. Egg washed out. Now there was a big embryo
inside egg. Good circulation of blood-elements, heavy pigmentation. Very close to
the hatching point.
Sixth drying on 15 Mar. 59. Still in peat. (I have one pair and
need no more fry of this species).
