Volume 86, Issue 2
August 1977, pages 73-142
pp 73-80 August 1977
A few taxa of the tribe Monosteroideae have been re-examined to find the possible utility of the typology of sclereids as a diagnostic character in the identification of doubtful taxa. From the present study it is clear that the presence or absence of sclereids in species ofRhaphidophora andScindapsus is very useful in indicating the sclereid approach to taxonomic problems within the smaller group of taxa than the family as a whole.
pp 81-85 August 1977
A new species ofEnteropogon coimbatorensis is described with illustrations The genus as represented in India is reviewed and a key presented.
pp 87-91 August 1977
Disruption and hypertrophy of cortical cells due to the migration and movement of larvae ofMeloidogyne graminicola partly contributed to the development of knots in rice roots. Hyperplasia of protophloem and abnormal xylem proliferation caused swelling of stele at sites of nematode attack and establishment. In tolerant rice varieties, poor giant cell formation caused delay in nematode development and in the resistant rices, nematode activity was further inhibited due to cell necrosis.
pp 93-97 August 1977
Mutants showing transformation of stamens into carpels were located in the progeny of desynaptics, inPennisetum typhoides. The mutant character varied in its expression in the different regions of the ear head. The transformation of the stamen into carpel was either partial or complete. This mutant condition was inherited as a single recessive gene controlled one. Occasional formation of two seeds from the same spikelet indicates the functional ability of some of the extra carpels.
pp 99-106 August 1977
A study of the nodal organization of 29 members of this order revealed four nodal types: I. Trilacunar three-traced, II. Bilacunar three-traced, III. Bilacunar two-traced and IV. Unilacunar one-traced. Trilacunar three-traced condition has been observed in 25 out of 29 species investigated. Whereas bilacunar two-traced condition is represnted by some half a dozen species, bilacunar three-traced condition and unilacunar one-traced conditions have been observed only inGeranium robertianum andLinum usitatissimum respectively. It is significant to note thatGeranium robertianum in addition shows a trilacunar three-traced and bilacunar two-traced conditions. Trilacunar three-traced condition is considered to be basic for this group and it is believed that the unilacunar one-traced condition is derived by approximation and coalescence of the laterals with the median, followed by the obliteration of their gaps. Such a tendency has been observed in some members of this group and a reduction series has been traced. The mode of branching in Geraniaceae is referred to as sympodial. This has been confirmed by the behaviour of the vascular cylinder at the node.
pp 107-116 August 1977
Himalayan populations of an advanced leptosporangiate fern,Hypodematium crenatum (Forsk.) Kuhn contain three cytotypes: diploid, triploid, and tetraploid. This paper describes spore germination and genotypically determined developmental and morphological plasticity of the gametophytes of triploid sporophyte. While the haploid and diploid gametophytes from the diploid and tetraploid sporophytes developed normally, those from the triploid exhibited an interesting array of morphogenetic alterations under the same culture conditions. These included formation of twin and multiple protonemata, displacement of metaphase spindle during successive mitoses, inhibition and/or delayed rhizoidal differentiation, lack of spore polarity and hypertrophy/allometric growth of protonemal cells.
pp 117-126 August 1977
The arrangement and the structure of the foetal membranes ofScotophilus heathi at full term are described. The yolk sac has collapsed resulting in the reduction of the lumen into streak-like spaces. The splanchnopleure is highly folded and the mesodermal cells are enormously hypertrophied and vacuolated. These changes give the yolk sac a gland-like appearance. A small abembryonic segment of the yolk sac remains trilaminar and lies freely in the persistent uterine lumen on the mesometrial side. The parietal layer of chorion with hypertrophied trophoblastic cells forms an accessory syndesmochorial placenta by coming into intimate contact with the uterine endometrium on the lateral sides of the uterus. The chorio-allantoic placenta is discoidal, antimesometrial, labyrinthine and haemomonochorial with only syncytiotrophoblast lining maternal vascular channels. A PAS-positive membrane is a permanent component of the placental barrier, and this lies embedded in a cytoplasmic lamina of syncytiotrophoblast. The PAS-positive membrane is porous.
pp 127-133 August 1977
The present paper incorporates two new species of the genusTabanus Linnaeus,viz., T. meghalayensis andT. miniatus and one new species of the genusHaematopota Meigen,viz., H. nigrifrons along with notes on three other species obtained from Meghalaya, India.
pp 135-138 August 1977
Microhyla chakrapanii sp. nov. andMicrohyla inornata Boul. are being described and reported respectively from the Andaman Island.
pp 139-142 August 1977
Changes in RNA, proteins, total free amino acid, ammonia and urea levels were measured in the cerebral, pleuropedal and visceral ganglia of normally active and nine months aestivated snails. RNA, proteins and total free amino acid levels increased on aestivation. Ammonia level showed a decrease on aestivation whereas the level of urea increased in the pleuropedal and visceral ganglia. However, a decrease in urea contents of cerebral ganglion was recorded on aestivation.