My work falls broadly into three groups of
subjects:
1. Studies on the determination of secondary sex
characters in invertebrates : papers 2, 3 and 4.
These papers describe research on one of the first
problems which engaged my attention : the causal determination of the differentiation of secondary sex
characters in invertebrates. While I was a student at
Naples in 1938/9 I was impressed by the problem of
parasitic castration and sex reversal in crustacea.
The problem has great physiological and genetic interest
it has also great complexity. This became apparent to me
when I found that the effects of epicarid isopods on their
prawn hosts is quite unlike the action of similar isopods
on Upogebia, this latter animal showing all the familiar
features of sex reversal when parasitised. The castration
of unparasitised prawns by means of X -rays gave evidence
that the cyclically developed female secondary sex
characters are dependent on the presence of a maturing
ovary for their differentiation : the same situation was
found, thong of published, for the adult female
characters of the crab Pachygrapsus, though this animal
undergoes sex reversal, male to female, on being
parasitised. It was hoped that castration of males might
be accomplished by means of X -rays since this would
supply crucial evidence for the resolution of the whole
problem. However, too high a level of irradiation. is
necessary for castration of male crabs, which die before
completing a further moult. Surgical castration likewise
proved impracticable and the problem was left in this
state.
2. Studies in chromosome cytology : papers 5,6,70,9,10,
11,14,(16,17),19,20 and 21.
My interest in chromosome cytology, originally
aroused by Dr J.R.Baker and Dr E.B.Ford,F.R.S., at Oxford
2.
and further stimulated by contact with Dr C.D.Darlington,
P.R.S., then of Merton,London, led me to study a number
of problems in this field. It is with these problems that
the main bulk of my papers are concerned.
Paper 6 demonstrated that a mmltiple chromosome
mechanism determines sex in the earwig. The situation
is complicated by the fact that males may have two
alternative chromosome constitutions and that the Y
chromosome in this species is dicentric :the mechanism
is considered to be related to the abnormal sex ratios in
earwigs which are found in the wild.
Paper 8 describes the behaviour of a supernumerary
autosome at meiosis in the grasshopper Mecostethus.
Paper 9 describes how a fertile plant hybrid has
arisen by the hybridisation of two autopolyploid species : this mechanism is an alternative means of arriving at an
alloployploid constitution.
Paper 10 describes the discovery of low temperature
sensitive heterochromatic segments of the chromosomes of
newts both at mitosis and meiosis and leads to the inference that desoxyribose nucleic acid ix plays an important
role in chromosome spiralisation.
Paper 11 describes _the upsets to the spindle
mechanism at mitosis which can arise as a result of
exposure of newt cells to low temperature or to the action
of colchicine.
Paper 14 demonstrates that the centromere is not
necessarily a barrier to chiasma interferenee at meiosis,
as was previously held to be the case. This was first
shown for the mosquito Culex and has subsequently proved
true for many other animal.
Paper 19 shows how chiasma interference across the
centromere is suppressed waen multivalent chromosome
associations are formed at meiosis.
Papers 20 and 21 describe the reduction in chiasma
frequency and the localisation of chiasmata in hybrids
between geographical races of newts. Evidence is also
given of the origin of a chromosomal translocation which
distinguishes the chromosome complement of one race
from the other two and which can act as a barrier to
genetic leakage between these races.
Papers 16 and 17, which do not rightly fall under
the heading of chromosome cytology, are nevertheless_
related to this theme since they are concerned with the
possibility of .a connection between heterorshromatic
chromosome segments, ribose nucleic acid synthesis and
growth rate determination.
3. Experimental work with giant nuclei : papers (12, 13),
15, 18, 22, 23.
Partly as a result of a controversy over the
distribution of nucleic acid in the cell (papers 12 and
13) and more generally because, having worked for some
years in the field of descriptive cytology and cytogenetics, 1 was impressed with the need for an experimental
attack on the many outstanding and general problems
concerning the cell nucleus, i turned my attention three
years ago to the exploitation of giant nuclei.
A great deal of this work is not yet ready for
publication : it is the general line of research in
which I an most actively engaged at the present time.
Since, however, a number of observations have already
been made, these are summarised in a final manuscript
entitled " Experimental studies on amphibian oocyte
nuclei ". This should be read as an introduction to my
published papers in this field.
LIST OF PUBLICATIONS:
1. 1938. "GUI size in millipedes ". NATURE, 141, 247 ||
2. 1939. "The absence of a sex -hormone controlling
regeneration of the hectocotylus in Octopus
vulgaris Lam. ". Pubbl.Staz.zool.Napoli, 18, 15 ||
3. 1940. "The effects of castration by parasites and .K-rayti
on the secohdary sex chcracters of prawns ".
J. exp. Biol., 17, 168.
|| 4. 1940. (with F.G.i.Knowles) "A change in the chromatophore pattern of crustacea at sexual maturity ".
J. exp. Biol., 17, 262.
|| 5. 1940. "The chromosomes of the cymothoid isopod Anilocra"
Çuart.J.micr.Sci., 82, 327.
|| 6. 1941. "The sexTdetermining mechanism of the earwig,
Forficula.auricularia ". J.Genet. 41, 349.
|| 7. 1941. "Determination of sex in Scalpellum ".
-NATURE, 148, 258 .
|| 8. 1941. "A trisomic grasshopper ". J.Hered. 32, 296.
|| 9. 1941. "The cytology of Gaulthettya wisleyensis (Marchant
Rehder: a new mode of species formation."
An.n.Bot.Lond.,N.S.5, 579
|| 10. 1942. "Heterochromatin in Triton ". Proc.roy.Soc.
B. 130, 324.
|| 11. 1943. (with H.N.Barber) "The effects of cold and
colchicine on mitosis in the newt ". Proc. roy.
Soc. B. 131, 258.
|| 12. 1943. "Distribution of nucleic acid in the cell"
NATURE, 152, 503
|| 13. 1944. (with 11.:.Barber) "Distribution of nucleic acid
in the cell ". HATURE, 153, 109.
2.
|| 14. l947.(with G. _'ontalenti) "Chiasma interference in
Mosquitoes". J. Genet., 48,119.
|| 15. 1948. "Alcune proprietà fisiche della membrana nucleare ".
Ricercha Scientifica, 18, 1.
|| 16. 1948. "Ribose nucleic acid in the Drosophila egg ".
NATURE, 161, 440.
|| 17. 1949. "Cleavage rate, oxygen consumption and ribose
nucleic acid content of sea urchin eggs ".
Biochem.et Biophys..cta, 3, 92.
|| 18. 1949 (with J.T.Randall,- . .S., and S.G.Tomlin) "An
electron microscope study of the nuclear membrane"
NATURE, 163, 280.
|| 19. 1949. "Chiasma interference in diploid, tetraploid and
interchange spermatocytes of the earwig ".
J. Genet. 49, 209.
|| 20. 1950 (with H.Spurway) "Hybrids between some members of
the Rassenkreis Triturus cristatus ".
EXPERIENTIA, in press.
|| 21. 1950 (wroth H.Spurway) "A study of meiosis in interracial hybrids of the newt Triturus cristatus ".
J. Genet. in press.
|| 22. 1950 (with GiL.Brown and G.Leaf) "The chemical nature
of nuclear sap ". NATURE, in press.
|| 23. 1950 (with S.G.Tornlin) "Experimental studies on
amphibian oocyte nuclei.l. Invettigation of the
structure of the nuclear membrane by means of
the electron microscope". Proc.roy.Soc.B, in press
