SCIENTIFIC SUMMARY. 
427 
influence of iodine they lose their colour and become more brilliant and 
refractive. The third forms always carry a nucleus, which in its turn 
possesses a nucleolus, the latter being disk-like in shape, while the former 
is a spherical cell. The fourth series of morphological elements, the 
reproductive cells, are of an oval or circular shape, filled with homogeneous 
contents, colourless, more or less refractive, about of an inch in dia- 
meter, but occasionally twice as large. Their number is not constant, but 
varies from ten to twenty, or more, and they have been frequently observed 
both with and without the nucleus in its spheruliferous state. When 
iodine is added to them, they become tinged with an amber hue, and 
occasionally present granular contents ; a claret hue is sometimes produced 
by this re-agent, but this is never of so deep a colour as to render the 
bodies liable to be mistaken for starch granules. Mr. Carter also alludes 
to the presence of chlorophyll cells, and seems to imply that these latter are 
identical with th z granules of Amoeba, and the amoebous cell of Spongilla. 
The Law of the Production of the Sexes in Animals . — Professor Thury’s 
memoir has been partly translated by Mr. W. S. Dallas, F.L.S. It is 
already known to most of our readers that the former naturalist lately 
advanced some very peculiar views as to the question, How are the different 
sexes produced. He believes that the earlier ova formed in the ovaries of 
all animals are in an imperfect condition, and if in this state they be fer- 
tilized, the result will be the production of a number of females ; if, 
however, the act of fecundation be delayed, males only will be developed. 
Hence he assumes that, among mammals, if the fertilization of the ovum 
occur at the commencement of the rutting season, females will be pro- 
duced ; if at the termination of this period, males only. It would appear 
that his doctrine has been corroborated by the results of several experi- 
ments. For our own parts, we are extremely sceptical as to the truth 
the discovery ; nevertheless, as they may be of interest, we give the fol- 
lowing series of “practical observations,” which constitute the second 
portion of Professor Thury’s memoir : — (1) Sex depends on the degree of 
maturation of the ovum at the moment of its fecundation. (2) The ovum 
which has not attained a certain degree of maturation, if it be fecundated, 
produces a female ; when this degree of maturation is passed, the ovum, if 
fecundated, produces a male. (3) When, at the rutting season, a single 
ovum separates from the ovary to descend slowly through the genital 
canal (as in uniparous animals), it is sufficient that the fecundation takes 
place at the commencement of the rutting season to produce females, and 
at the end to produce males — the turning point of the ovum occurring 
normally during its passage through the genital canal. (4) When several 
ova separate successively from the ovary during a single generative period, 
the first ova are generally the least developed, and produce females ; the 
last are more mature, and furnish males. But if it happens that a second 
generative period succeeds the first one, or if the external or organic con- 
ditions change considerably, the last ova may not attain to the superior 
degree of maturation, and may again furnish females. Hence it happens 
that the application'of the principle to animals which are multiparous is 
far from easy. (5) In carrying out experiments it will be necessary to be 
