482 
NAT 
URE" [ Oct. 13, 1870 
Besides the branchlets, which—as in the hydroids generally— 
support the hydranths (plypites), others are developed in 
abundance from all parts of the hydrocaulus. These commence 
just like the ordinary branchlets, as offshoots from the hydro- 
caulus, and consist as usual of a continuation of the ccoenosarc, 
invested by a chitinous perisarc. Unlike the ordinary branchlets, 
however, they never carry a hydranth, but are destined for the 
multiplication of the colony, by a process of spontaneous fission. 
After the entire branchlet has attained some length, the con- 
tained ccenosare continues to elongate itself. In doing so it 
ruptures the delicate pellicle of chitine which closes the 
extremity of the branchlet, and extendsitself quite naked into the 
surrounding water. 
It is now that the process of fission commences. A constriction 
takes place in the ccenosare at some distance below its free 
extremity, and in the part still covered by the chitinous perisare. 
The constriction ranidly deepens, and ultimately cuts off a piece 
which slips entirely vut of the perisarcal tube and becomes a free 
zooid, while the surface of disseveration soon heals over, and the 
axial cavity of the free frustule becomes here as completely 
closed as at the opposite end. 
The detached fragment strikingly resembles a A/azz/a in all 
points except in the total absence of vibratile cilia. It attaches 
itself by a mucous excretion from its surface to the walls of the 
vessel, and exhibits slight and very sluggish changes of form. 
The further history of the fission-frustule was traced, and the 
important and unexpected fact was shown that it never directly 
develops a hydranth. After a time a bud springs from its side, 
and it is from this bud alone that the first hydranth of the new 
colony is developed. 
The bud which thus becomes developed into the primordial 
hydranth remains attached to the fission-frustule which forms for 
it a sort of hydrorhiza, but which would seem ultimately to perish 
and give place to true hydrorhizal filaments. In the meantime 
the primary bud emits others, and a complex branching colony 
is the result. 
The author compared the fission-frustule to the free medusoid 
element of other hydroids with which it agreed in never beco- 
ming directly developed into a new trophosome, but from which 
it differed in the very important fact of taking no part in the true 
generation of the hydroid and in giving origin to a new colony 
only by a simple non-sexual multiplication. 
Observations on Protandry and Protogyny in British Plants. 
—Alfred W. Bennett, F.L.S. The arrangement of the repro- 
ductive organs in hermaphrodite plants, the presence in the same 
flower of both pistil and stamens, suggested to the minds of the 
older botanists no other idea than that of fertilisation. It is, 
however, now generally admitted that, even in hermaphrodite 
flowers, cross-fertilisation is the rule, self-fertilisation the excep- 
tion. _Two sets of facts have been especially observed,—in 
particular by Darwin in this country, Hildebrand in Germany, 
and Delpino in Italy,—to favour cross-fertilisation in herma- 
phrodite flowers ; the phenomena of dimorphism and trimorphism, 
and the special arrangements which render it easier for the pollen 
to be brushed off by insects visiting the flower than to fall on its 
own stigma. But, besides these, another arrangement exists by 
which self-fertilisation is hindered, the simple fact that the 
stamens and pistil belonging to the same flower are frequently 
not ripe, so to speak, at the same time. The terms Profandry 
and Protegyny used by Hildebrand to express, in the one case 
the development of the stamens before the pistils, in the other 
case the development of the pistil before the stamens, are so 
convenient and expressive that they have been adopted in this 
paper; the term by which he expresses that the two organs 
are matured simultaneously, ‘‘ Non-dichogamy,” does not seem 
so happy, and the author proposes to substitute for it Syrzacmy— 
the phenomena of Protandry and Protogyny forming together 
that of “eteracmy. 
The most frequent arrangement appears to be that the pollen 
commences to be discharged from the anthers at a longer or 
shorter interval before the maturing of the stigma. In some cases 
there still remains a certain quantity of pollen in the anthers when 
the stigma is ready to receive it; in other cases, the anthers have 
either withered up or entirely dropped off before fertilisation of 
the ovules can possibly take place. Synacmy, or the contem- 
poraneous maturing of the reproductive organs, is nearly as fre- 
quent as protandry ; while protogyny is a phenomenon of far less 
common occurrence. The two extremes among the species ob- 
served may be stated to be Campanula rotundifolia and Scrophu- 
aria aquatica, In some Natural Orders, as Legzwiinose and 
Labiate, all the species examined, with scarcely an exception, 
range themselves in one or other of the three classes; while in 
others, as Rosacee, they are distributed over all three, and in _ 
some instances, even closely allied species of the same genus — 
differ in this respect, as, for instance, Potentilla and Ranunculus, 
Careful observations might even, the author thinks, in some 
cases, derive from this point a useful diagnosis of difficult 
species. 
In those Natural Orders in which the flowers are furnished 
with two sets of stamens of different lengths, it is most usual for 
the longer ones to discharge their pollen at an earlier period than 
the shorter ones, and they probably have different functions to 
perform. This is commonly the case with Crucifere, Carophyl- 
lee, Geraniacee, and Onagrarice, but not, apparently, with Ladiate 
or Scrophularinee. The same phenomenon is found in those orders 
where the numerous stamens are arranged in different whorls, as 
Ranunculacee and Rosacee. The author then gave an account 
of a number of observations on British wild plants. 
SrcTion E.—GErOGRAPHY 
The Ruined Indian Cities of Central America.—Captain Car- 
michael. The author commenced by giving an account of the im- 
pression caused on first beholding these ruins, and showed how 
the question involuntarily suggested itself as to the originality of 
their architectural designs, and stated that a certain familiarity 
of trait and outline was invariably recognised ; and that in his 
opinion, formed from personal inyestigation, the architecture of 
the Aboriginal Indians of Central America was but a diversified 
reproduction of that of Eastern countries. He then pointed 
out a number of similarities in their architecture, designs, 
customs, &c., to nations of the East; and showed how, as a 
general rule, it was very difficult to explore these ruins owing to 
the hostility of the existing tribes of Indians, 
As regards their antiquity, he assigned to many of them an 
earlier foundation than that accorded to them by Stephens and 
Squier, and adduced some very convincing, if novel, proofs in 
support of his theory. The picture he drew of the palaces of 
Quiché in Guatemala fully bore out the statement of Torque- 
mada that they rivalled those of Montezuma; and he showed 
that if that city—one of some eight hundred years’ standing— 
was in such a perfect state of conservation some fifty years ago, 
that the padre of a neighbouring Indian village who then walked 
among its streets and palaces, imagined himself in Spain, what 
must be the era of those numerous cities compared with which 
Quiché was modern ? 
He then pointed out the great length of these ruined cities, 
and added that in connection with this a remarkable fact had 
seemingly been overlooked by most Central American writers, 
viz., that the stone buildings whose ruins we now find extant 
were used as temples, palaces, and public offices generally. the 
poorer inhabitants living in huts of a perishable nature ; an 
arrangement which represented’an almost incredible amount of 
population. He then analysed the various elements composing 
the architecture of the ruined buildings and monuments, and 
gave an interesting account of the various uses to which the 
teocali and tumuli were put by the Toltecan and Aztec priests, 
viz., for sacrificial and burial purposes, to serve as beacons, for 
warlike defences, &c.; and explained the relations between 
the temples and alcazars or palaces, and offered a few hints as to 
the deciphering of the hieroglyphics, a subject to which he has 
paid much attention, and for which he is specially qualified 
from his knowledge of the Maya or Indian language, showing 
that they were chiefly the works of the Indian priesthood ; and, 
above all, were intended to inculcate moral and religious pre- 
cepts, chronological events being made quite subservient to them. 
He then referred briefly to the round towers which contained 
the estufas for the sacred fire of Montezuma, in connection with 
the worship of the Sun, and passed on to explain the nature and 
significance of the various hideous and awe-inspiring idols to 
whom the human sacrifice was offered on the summit of the 
teocali, and stated it as his belief that these idols, as well as the 
planed stones, were carved with clay or flint instruments, as he 
had often found flint and obsidian implements, but in no instance 
an instrument of metal. 
Referring to the state of decay in which they were mostly 
found, he stated that there were ruins which had never been 
visited by the Spaniards at the time of the conquest, and ex- 
pressed it as his opinion that their crumbling and ruinous 
condition was mainly brought about by the earthquakes so 
