NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
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quantity remaining close to the upper extremity of it. The number of pro--
cesses which thus come to form a capitulum at the end of the tube varies from
four to six as a rule. They gradually elongate and assume a slender fusiform
outline with a pointed extremity, and, as they do so, they become separated from
the germinal tube by a septum and traversed in their length by two or three
others (Plate II, fig. 7). Each process thus comes to consist of three or four
cells. The terminal pointed one next gives origin to two or three minute
sterigmata at its apex, and each of these in its turn develops a long slender
sporidium (Plate II, fig. 16). These conjugate just as the sporidia of Tilletia or
Entyloma, union as a rule taking place between sporidia of distinct processes
(Plate II, figs. 11, 12, 13). Conjugation takes place both before and after de--
tachment of the sporidia from the promycelium. The uniting tube usually is
situated towards one or other extremity of the sporidia and is often of con-
siderable length and curiously sinuous course (Plate II, fig. 14). The sporidia
are full of finely molecular protoplasm and are extremely long and slender,
measuring in many cases as much as 21 u. in length by 0.9 u in breadth.
After conjugation has occurred the greater part of the protoplasm appears to
pass into one or other of the united bodies which grows considerably longer, and
at the same time transverse septa appear in it and in the other one. Finally,
secondary sporidia are given off laterally from the primary ones, varying in form
in different instances, in some cases being very short, in others elongated and
very similar to their parents.
When the spores are cultivated in a nutritive fluid, such as strong decoction
of Nymphœa leaves, the phenomena attending germination differ in certain
points of detail. All the earlier phenomena are of the same character as those
which have just been described up to the development of the primary sporidia.
After this deviations from the previous type tend to occur. Conjugation is by
no means of such constant occurrence, and formation of secondary sporidia
frequently occurs from unconjugated primary ones (Plate II, fig. 12). The
secondary sporidia, which here appear to be always similar in form to their
parents, in their turn give origin to a new series of slender spindles, and, the
same process being continued, ramified series of filaments, built up of connected
spindles, gradually arise. The phenomena are, in fact, precisely parallel to those
described by Brefeld as attending the cultivation of the spores of other forms of
Ustilagineœ in nutritive fluids in place of water. 1 T h e c a p a c i t y f o r c o n t i n u e d
saprophytic in place of parasitic existence affords the only explanation of the
persistence of the parasite from year to year in many cases; for example,
where it is present in tanks containing Nymphœa lotus and Nymphœa stellata
alone, there are periods of many months during the cold and hot seasons in
which not a single leaf, or trace, of the host-plant is present to afford accommo-
1 Botanische Untersuchungen über Hefenpilze Von Dr. Oscar Brefeld: Leipzig, 1883.
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Scientific Memoirs by Medical Officers of the Army of India.
corresponding to sporidia, but as portions of the promycelium, and the constant
occurrence of conjugation in the bodies developed from them shows that these
really are primary sporidia, and not secondary ones derived from such bodies.
The promycelium is thus much more complicated than in either Tilletia or
Entyloma, consisting not merely of a simple septate germinal tube, but of such
a tube and a series of septate terminal branches. The peculiar rostrate cha-
racter of the spores is also very distinctive, but it is of course a mere result of
the fact that the spores are here developed subterminally, and not intercalarly,
as they are in Entyloma. The above characters appear to entitle the parasite
to be regarded as forming the type of a new genus which I propose to name and
define as follows:—
Rhamphospora (Family USTILAGINEÆ).
Spores isolated; produced subterminally; beaked; promycelium consisting
of a long germinal tube with terminal branches bearing apical sporidia.
Rhamphospora Nymphœa.
Characters those of the genus; habitat, the leaves of Nymphœa stellata,
Nymphœa lotus, and Nymphœa rubra.
CALCUTTA;
The 15th April 1887.
On an Entophytic Alga occurring in the leaves of Limnanthe
-mum indicum, with notes on a peculiarly parasitic variety of
Mycoidea.
BY
SURGEON-MAJOR D. D. CUNNINGHAM, M.B.,
SPECIAL ASSISTANT TO THE SANITARY COMMISSIONER WITH THE GOVERNMENT OF INDIA.
(With Plates I and III.)
The Entophytic alga described in the following pages was first observed in
the leaves of Limnanthemum indicum in tanks in the Botanical Garden,
Calcutta, in October 1886. At that time it was extremely abundant in some
tanks and caused very conspicuous effects in the leaves of its host. The
infected leaves showed patches of yellowish discolouration of the upper surface,
sometimes isolated, sometimes in groups and slightly elevated above the level
of the surrounding normal tissue (Plate III, fig. 1). On removing the leaves
from the water the discolouration was found to be confined to the upper surfaces
of the leaves, and on examining the affected areas under simple lens, they were
found to differ from the surrounding ones in containing great numbers of large,
brilliant green rounded bodies situated beneath the epidermis. On making thin
horizontal sections from the surface of the leaf and examining them under
somewhat higher powers, these bodies were found to be large, oval or spherical
cells situated in the substomatic spaces. In the discoloured patches such cells
were present in immense numbers and so closely distributed that almost every
substomatic space contained one and in some cases two of them (Plate III,
fig. 2). They were not, however, absolutely confined to the conspicuously
discoloured areas, as isolated specimens frequently occurred at wide intervals
over the apparently normal surfaces around. The individual cells varied greatly
in the character of their contents, some having a great, central, clear, colourless
area surrounded by a clear pale green peripheral zone containing a few starch-
like corpuscles, others being deep green and granular throughout, others also
deep green, but with the contents presenting a mulberry-like nodulated appear
-ance and still others in small numbers of various tints ranging from pale yellow
to strong reddish orange and densely filled with large amyloid bodies. At first
sight they presented so many features resembling those of Cohn's Chloro
-chytrium Lemnæ that it appeared probable that they belonged to the same
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genus, but on a study of their life history it was evident that this was not the
case, but that they were representatives of a closely allied and apparently as yet
undescribed one.
The leaves of Limnanthemum indicum in which they occur are charac-
terised by the enormous number of stomata in the superior epidermis and by
the presence of comparatively large substomatic spaces between the subjacent
palisade cells (Plate III, fig. 4). Due to this the tissue immediately beneath the
superior epidermis is of an extremely open, almost reticulate character (Plate
III, fig. 6). The algal cells are absolutely confined to the substomatic spaces
which they deform in various ways as they increase in size and press upon the sur-
rounding tissue elements. Beyond the distortion arising in this way, the presence
of the foreign bodies produces no appreciable effect on the tissues save causing
a permanent wide patency of the stomatic orifices. There is no sign of injury
of the surrounding palisade and ordinary parenchymal cells, which in general
aspect and amount of chlorophyll content differ in no respect from those in
areas which have not been invaded by the alga. Due to the mutual pressure of
the algal and host cells many of the former in many cases gradually lose their
originally evenly rounded contour and come to present irregularly lobed or
even angular outlines. They naturally vary very considerably in size accord-
-ing to the stage of development, but mature green specimens give an average
of 59 µ by 50 µ. On making vertical sections of the affected leaves the rela--
tions of the algal cells to the surrounding elements appear very clearly. They
press laterally on the neighbouring palisade cells and above are in close contact
with the stomatic openings and the under-surfaces of their guard cells (Plate III,
fig. 5).
The cells differ greatly in appearance in different cases, as has been already
mentioned, and this difference is connected with their age and with the ultimate
developmental changes which they undergo in connection with seasonal influ-
ences. Young cells have a delicate cell-wall surrounding a thin layer of pale
green protoplasm within which is a great colourless area containing a single
nucleus. Amyloid granules are present in gradually increasing numbers in the
peripheral green layer (Plate III, fig. 3). The green colouring increases in inten-
sity and extends more and more into the central portion, and the contents thus
gradually become of a uniform deep green and of coarsely granular consistence.
On removing the colouring matter with alcohol and subsequently staining the
presence of a single nucleus is still demonstrable up to this stage. Repeated
processes of nuclear division now set in and the contents are thus gradually
converted into a continuous mass of protoplasm, including a very large number
of distinct nuclei (Plate III, fig. 8). A differentiation of the cytoplasm now
occurs and each nucleus becomes gradually invested by a separate layer proper
to itself, the entire mass of contents as the process goes on coming to present
a lobulated, mulberry-like appearance. The nucleated protoplasts which have
Medical Officers of the Army of India.
37
sequently by George Kiebs. 1 A t t h e s a m e t i m e , h o w e v e r , i t p r e s e n t s c e r t a i n v e r y
distinctive features separating it from that genus. The most important of these
distinctive points are, first, the fact that the zygospores and zoospores do not
germinate as the zygospores of Chlorochytrium Lemnæ and the zoospores of
Chlorochytrium knyanum do; and second, that the zoospores become free within
the zoosporangium in place of being discharged from it in a common gelatinous
investment from which they are subsequently freed, as is the case with those of
Chlorochytrium. Taking these facts into consideration, I would propose to refer
the present alga to a distinct genus, Stomatochytrium. The definition of the
genus and species may stand as follows
: —
Stomatochytrium (Family PROTOCOCCEACEÆ).
Entophytic: zoospores conjugating; neither zoospores nor zygozoospores
germinating; zoospores liberated within the Zoosporangium.
Stomatochytrium Limnanthemi: characters those of the genus; habitat,
the substomatic spaces in the leaves of Limnanthemum indicum.
The characters and life history of this organism appear to me to be very
instructive in connection with the true parasitism which was ascribed to Chlo-
rochytrium by Cohn and to various other similar algæ by other observers. The
phenomena presented by Stomatochytrium appear very strongly to support the
views off Klebs, who maintains that in such cases we have not to do with true
parasitism, but merely with entophytism. In the present instance there is
absolutely nothing to show that the intrusive elements abstract organised mate-
rials from the host tissues—nay more, there is absolutely nothing to show
that they abstract materials of any kind from them. As has been already
pointed out, the presence of the algal elements fails to produce any appreciable
effect on the surrounding tissue elements beyond displacements and distortions
arising as the result of mechanical causes. In this case, too, there is no injury to
the integrity of the tissues connected with the access of the algal elements
to their site of subsequent development, as there is in the case of
Chloro-chytrium, for the substomatic spaces are directly invaded by means of the
stomatic orifices. Everything here points unequivocally to the correctness of
the view maintained by Klebs, that in such cases the algæ only differ from
common ones in that they have gradually become specially adapted to living in
specially-protected sites, the protection afforded by the surrounding masses of
host tissue and not any derivation of nutritive materials from them being the
real determinant of the entophytic habit. There is certainly in Stomatochytrium
no evidence of any abstraction of nutritive materials from the host tissues. At
the utmost we are dealing with a diversion of nutritive materials which ought
properly to have been devoted to the host, and not with any abstraction of mate-
rials which have ever formed a real part of the host, and when the very
1
B o t a n i s c h e Z e i t u n g , 1 8 8 1 , N o s . 1 6 t o 2 1 .
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Scientific Memoirs by Medical Officers of the Army of India.
tissues it is hard to determine. At certain points in some specimens, however,
continuous penetration of the lamina throughout the greater extent of its thick-
-ness by unequivocal algal elements connected with those of the superior sub-
epidermal thallus can be recognised, the peculiar green or yellow colour of the
contents distinguishing the parasitic from the host elements very clearly (Plate
I, fig. 7). It appears that, as a rule, penetration of the deeper portions of
the laminar tissue only occurs at isolated points by means of series of cells
which serve to connect the inferior surface of the superior, subepidermal thallus
with the scattered masses of cells above the inferior epidermis giving origin to
the inferior tufts of fertile filaments.
We have here to deal with intrusive algal elements which, both as regards
their relation to the host tissues and the effects which they produce on them,
clearly differ greatly from those of Stomatochytrium. The algal elements here
do not occupy normal interspaces in the tissue, but force their way between
normally closely adapted structures breaking up the continuity of the laminar
structure. They produce effects on the tissues of the host not limited to mere
distortion from mechanical pressure, but giving rise to such interference with the
normal process of nutrition as to lead to death, and ultimate disintegration in
masses of tissue in which mere mechanical distortion is entirely absent. The
effects are certainly characteristic of parasitism as distinguished from simple
entophytism. It is impossible to suppose that in this case the nutrition of the
intrusive elements can be carried on without interfering with that of those of the
host. They are not, like those of Stomatochytrium, so superficially situated as
to have a direct relation to the outer world. On the contrary, they are, save
where fertile filaments emerge, buried in dense masses of tissue. Due to their
distribution they must at all events interfere with the nutrition of the host ele
-ments by misappropriation of materials properly destined for the use of the
latter. Whether the interference goes further than this, whether it advances to
the stage of appropriation of organised products developed by the host tissues,
remains uncertain, but the instances in which large masses of the intrusive
elements appear to be almost or totally devoid of chlorophyll and yet in vigorous
growth strongly suggest that such higher parasitism really prevail.
CALCUTTA;
The 15th April 1887.
The Fly-catching habit of "Wrightia coccinea."
BY
SURGEON A. TOMES, M.D.,
BENGAL MEDICAL SERVICE.
(With Plate VI.)
In a neighbour's garden at Midnapore are two fine shrubs of Wrightia
coccinea. They were in full bloom in April and May, and their handsome deep
red waxy-looking flowers were often observed to hold, entrapped, one or more
living and struggling flies.
Learning from Dr. King (who kindly identified the species for me) that the
peculiarity in question does not appear to have been noted by botanists hitherto,
I have been induced to investigate the mechanism of the trap with a view of
discovering the meaning of the habit.
The flowers of this Wrightia have a very strong attraction for insects.
This is owing to their gaudy colour, to their possessing a peculiar heavy vinous
smell, and to the secretion of a syrupy liquid which bathes their internal surfaces.
So strong is the attraction that while I was engaged in the dissection of a
specimen, a portion of the perianth lying on my table was promptly discovered,
seized, and carried off by a hungry cockroach.
The insects found entrapped were almost invariably common house flies
caught by the proboscis, but occasionally a rather large species of ant caught
by the neck, in a trap formed by the stamens (see Fig. I, pl. VI).
On certain days dozens of flies would be caught thus, while on others not
one would be seen.
On one occasion a single flower had succeeded in imprisoning four flies
all at once, while two flies were often to be found in the same flower.
The insects after capture were not digested, but died a lingering death, and
were devoured by red ants, which appeared to swarm over the tree. A fly which
I released from the trap after a long detention seemed to be none the worse
except for a bruised and swollen proboscis.
The "trap" is formed by the andrœcium in this way:—The flowers are
pentandrous; the 5 stamens, somewhat arrow-headed in shape, are of strong
woody consistence, and each is bordered by a stiff narrow wing or membrane
(see Fig. 3, pl. VI, a and b). They spring from the perianth, and converging
surround the pistil in the form of a cone, closely embracing it at its upper part. G
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For the upper half or two-thirds of their length they are closely in contact
with each other, laterally, by means of their winged edges (see Fig. 3, pl. VI),
but they are separated below by narrow slit-like openings, while at the base of
the cone below the tips of the wings and between the stout filaments are left
5 quadrangular openings of considerable size, through which the nectary can
easily be reached.
In every cone there are thus 5 slits, each of which constitutes a separate
trap for insects.
If a thread, a fine straw, or a bristle, imitating the proboscis of a fly, be
introduced into the interior of the cone through one of the basal openings and
then gently withdrawn in an upward direction, it will readily pass into the slit,
where, as traction continues, it soon becomes fixed. If now the hand be raised
still higher, it will be found possible to extract the bristle very slantingly through
the apex of the cone, where the points of the anthers give a little, and in the
process of withdrawal it comes into contact, first, with the sticky stigmatic
tissue, then with the pollen, some of the grains of which will be found adhering
to its point.
It seems to me that the action of the trap is purely mechanical. After
repeated experiments I could not discover any appearance of irritability or sensi
-tiveness of the stamens. Irritation of the interior of the cone had no effect in the
closer approximation of the adjacent wings, the width of the slit remained the
same even after capture of an insect. The slit-like interval between the wings
narrows from below upwards until the sides actually touch. The wings them-
selves are "set" somewhat inwards towards the long axis of the cone (Fig. 6,
pl. VI). They thus tend to fall together valve-like and the whole arrangement
is adapted to favour the wedging in of an impacted proboscis. There is plenty
of room for an insect to withdraw its head or proboscis through the large open
-ing at the base, and it is not easy to understand why entanglement should so
often occur.
Possibly while in the act of searching, the member becomes jammed, and
once caught in the slit all efforts except in one direction, directly upwards, as
has been shewn, only cause it to be held the tighter; so tight, indeed, does the
trap hold that once the struggles of a captured ant were seen to result in its
decapitation.
The free edges of the wings are smooth and hard. A lens reveals no teeth
or ridges, but they are seen to be finely ribbed longitudinally.
The shrubs have now ceased to blossom and want of material prevents
further enquiry at present. From the foregoing the plant clearly is not insecti
-vorous, and there is a strong probability that the fly-catching habit is accidental,
resulting from the arrangements to secure the fertilization of the species. In
the two specimens to which I have had access all the flowers we-re hermaphro-
Medical Officers of the Army of India.
43
dite, with perfect male and female organs, but their construction is such that
self-fertilization cannot easily take place. The anthers are introrse and dehis-
-cence apical, but the upper portion of the cone is so closely applied to and
around the stigma, that pollen could scarcely fall spontaneously upon the stigma;
in fact self-fertilization could only be effected at a mechanical disadvantage.
On the other hand, all the circumstances of the case appear to favour the idea
of fertilization by insect agency. But flies and ants are obviously not destined
to be the agents; these are caught and perish, while stronger ones, such as bees
for instance, or butterflies and moths, perhaps having a longer proboscis, may
be able to release themselves (and a long proboscis would be an advantage for
withdrawal through the apex of the cone) and so to carry away the pollen to the
next flower they visit. The fact that the stigma must be reached before the
pollen in the process of withdrawal supports this view. Pollen adhering to
the tip of a proboscis after its extraction from one trap would certainly be
wiped off upon the stigma of the next one in which it may chance to be ar
-rested. Such are the points that I have observed in connexion with this ap
-parently wanton destruction of insect life by the Wrightia , and the interpre
-tation they appear to suggest, but I by no means claim to have finally solved
the mystery, for I admit that I have never actually seen a bee or other larger
insect engaged in the flower, or in the act of releasing itself from the trap.
G2