396 
WNeATIORE 
[FEprRuaryY 25, 1897 
THE DISCOVERY OF ANOTHER CONNECT- watery fluid. The two generative cells, which have 
ING LINK BETWEEN FLOWERING AND 
FLOWERLESS PLANTS. 
N EWS has recently reached Europe, from Japan, of a 
botanical discovery of unusual interest and im- 
portance. Two investigators, Prof. Ikeno (Botan. Cen- 
trabl., 1897, 1) and Dr. Hirase (#é¢d., 2 and 3), working 
independently, have observed the formation of anthero- 
zoids—bodies which have hitherto been regarded as 
exclusively confined to flowerless plants—in two groups 
of gymnosperms. 
It is well known that in a large number of cryptogams, 
including all the higher forms, the process of fertilisation 
is intimately connected with the presence of water. The 
spores (or, at any rate, certain of them) give rise on 
germinating, sooner or later to cells from which free- 
swimming antherozoids are liberated. Each of the latter 
consists of a loosely coiled nucleus ensheathed in proto- 
plasm, which is especially abundant at the anterior end 
of the body, and from it arise the cilia which enable the 
antherozoid to move through water. 
In the flowering plants, on the other hand, with their 
special adaptations to a terrestrial mode of existence, it 
is of obvious disadvantage to depend on the precarious 
presence of water as the means of enabling the male 
sexual cell to find the female, and we find that the motile 
antherozoids are replaced by quiescent male cells, 
which are conducted to the female organs along a tube— 
the pollen-tube—which is a direct outgrowth of the spore 
-or pollen-grain. 
Now the gymnosperms, whilst they share with the 
rest of the flowering plants many characters in common, 
including the possession of a pollen-tube, yet differ from 
them in other important respects and approximate more 
nearly to the higher cryptogams. It is to the brilliant work 
of Hofmeister, more than forty years ago, that the recog- 
nition of this fact is primarily due, and it is, perhaps, a 
matter for surprise that a group occupying such an 
admittedly important position should not have been long 
ago subjected to a more searching scrutiny than it has 
received. It is true that Strasburger has added much to 
our knowledge ; but, perhaps, the first really illuminating 
discovery since Hofmeister’s time was that made by 
Belajeff in 1891, which was confirmed and extended by 
Strasburger in the following year. It was there shown 
that, whereas the similarity between the female pro- 
thallium and its products with the corresponding struc- 
tures in cryptogams had already been recognised, a closer 
investigation into the process of germination of the 
pollen-grain also yielded quite unlooked-for resemblances 
to the homologous stages in the lower plants, clearly 
confirming the near kinship of the two groups. 
But the presence of a pollen-tube, which would seem 
to render the formation of antherozoids superfluous, if 
not indeed directly disadvantageous, still appeared as 
one of the sharply-drawn distinctions between the zoido- 
gamous cryptogam and the siphonogamous phanerogam. 
It is in the successful bridging over of this gulf that the 
great importance of the new discovery lies. 
The two gymnosperms, Cycas vevoluta and Gingko 
4iloba, in which antherozoids have just been found, are 
both ancient types, and closely resemble each other in 
the mode of the formation of their male sexual cells. At 
first the pollen germinates much as in the other higher 
plants, forming a pollen-tube which penetrates the ovule, 
and containing a group of cells from one of which the 
antherozoids are ultimately derived. But unlike other 
forms which have been thoroughly investigated, the 
pollen-tube remains short, and although it may branch, 
it does not reach the archegonia in which the female cells 
are contained. The archegonia themselves lie round the 
base of a depression situated at the apex of the pro- 
thallium, and the space above them is stated to containa 
NO. 1426, VOL. 55] 
travelled to the end of the rudimentary pollen-tube, now 
become differentiated into antherozoids. The nucleus, 
which is large and egg-shaped, lies enclosed in proto- 
plasm, and the latter alone supplies the material for the 
formation of the coiled anterior portion of the body. 
Cilia are formed on the coil in great numbers, and are able 
to impart a progressive, rotatory motion to the anther- 
ozoid. Dr. Hirase, who studied their behaviour in Gzmgko 
while alive, was able to watch them actually moving, and 
probably the same is true of Cycas, although, owing to 
the material having been killed, this, of course, could not 
be tested in the case of the latter plant. They are large 
bodies, measuring about 82x 49 », and escape from the 
end of the pollen-tube, reaching the necks of the arche- 
gonia by swimming through the intervening water. 
In reading the short account, as yet published, there isa 
point of especial interest which strikes one, namely, that 
the plant must have already begun to eliminate the 
element of risk which a dependence on a mere chance 
supply of water entails, by itself secreting the liquid 
necessary to enable the antherozoid to accomplish its 
mission. As soon as this habit has been developed it 
becomes intelligible how, in these more primitive 
examples, the spore might proceed to swell and finally 
put out a protuberance on the side nearest the water- 
supply. And the more effectively this was carried through, 
the less would be the chance of missing fertilisation Thus 
it becomes comparatively easy to reconstruct, at any rate 
theoretically, the transitional stages between zoidogamy 
and siphonogamy. J, Bae, 
HUMAN INCUBATORS. 
N a recent number of L’///ustration an account 
is given of an incubator used for rearing delicate 
children. The apparatus designed by Dr. Tarnier, Pro- 
fessor of the Faculté de Paris, was first used, in the year 
1880, at the Paris Maternity Hospital: it is constructed 
on the same principles as the incubator used for hatching 
the eggs of poultry. 
The apparatus, as first designed, consists of a large 
cubical box of thick wood, standing on a pedestal. This 
box is divided into two compartments, of which the 
lower contains a reservoir of hot water, and the upper 
the bed of the infant. A movable glass shutter forms 
the top of the apparatus, through which it is possible 
to observe the changes occurring inside, and take the 
readings of the thermometer placed near the infant. 
One side of the compartment is so hinged as to open 
like a door. The whole of the upper part is warmed by 
means of the hot water underneath, the warm air rising 
through holes at each end of the bed, and escaping 
through orifices situated at the top. The temperature 
of the water is so regulated that the temperature of 
the apparatus never “exceeds 30 to 37° Centigrade. 
The weaker the infant is, the greater the temperature. 
required. 
Dr. Tarnier, with the help of his house surgeon, M. 
Auvard, lost no time in improving this apparatus. His 
latest design does not differ very much from the one 
described above ; it has, however, the advantage of being 
more simple in character, and also lighter i in construction. 
(Fig. 1.) The external dimensions measure 65 x 30 X 5¢ 
centimetres, the thickness of sides being about 25 mill 
metres. The upper part of the case is “divided into two 
sections, one being a wooden fixture, L, about 13 centi- 
metres wide, and having a circular opening 4 centimetres 
in diameter at its middle part, to which may be attached 
a small helix, H. The rotation of this helix indicates the 
existence of a draught of air through the case. The 
other section is a glass shutter, Vv, which also serves as 
door. 
The interior of the case is divided into a lower and 
