Volume 58, Issue 3
September 1963, pages 117-185
pp 117-127 September 1963
pp 128-136 September 1963
The extra-vacuolar nucleus is visible in a small percentage of living cells from 72–96 hour wort cultures. The vacuoles show a luminous boundary under dark ground illumination. The details observed in living nuclei could be stained with haematoxylin after fixation in iodine-formaldehyde-acetic acid mixture. The Feulgen-negative nature of the vacuole and the limitation of the Feulgen-positive material to the area bounded by the nuclear membrane would imply that the ‘centrosome’ described by Lindegren and Rafalko (1950) is the real nucleus. The nucleus ofS. bayanus conforms in its structure to those of higher organisms.
pp 137-147 September 1963
The life-history ofSpirocerca lupi, of dogs, had not been studied in India so far. Preliminary experiments with cockroaches and scarabaeid beetles have proved that the cockroach,Periplaneta americana, is insusceptible as an intermediate host, while the beetle,Gymnopleurus koenigi F., harboured free and encapsulated larvae, identifiable as those ofS. lupi, both as a natural and as an experimental infection.Euoniticellus (=Oniticellus)pallipes F. may also be another scarabaeid intermediate host. Two dogs, fed with 96 and 30 larvae from beetles, showed a nodule each, and 16 and 3 immatureS. lupi, in 5 months and 7 days, and 4 months and 24 days respectively. Eggs of the worm had not been expelled in the stool of either dog, and the prepatent period may therefore be longer than these. Reference is made to two reports, by other workers, of abnormal hosts ofS. lupi, the donkey, horse and goat with juvenile worms in India, and a premature child with male and female adults in the intestine as a result of pre-natal infection, in Italy.
pp 148-152 September 1963
The spores ofCystopteris fragilis are monolete with spinate exine and devoid of perine.
On germination a germ filament is produced which when 4–6 cells long has the terminal cell dividing obliquely twice to form an obconical apical meristematic cell. Marginal hairs are produced by young thalli. The apical cell is replaced by a multicellular meristem when the thalli become cordate. An apical cell stage is frequently omitted and spatulate, ameristic thalli develop a multicellular meristem directly.
The mature prothallus is cordate with a broad midrib and bears marginal and superficial unicellular hairs.
pp 153-164 September 1963
This paper describes the structure arrangement, development of root and the organization of its apex inI. coromandelina and some other species. Though nothing strikingly different from what has already been described by Campbell (1891) about the organization of root apex has been found, it has nevertheless become clear from the structure arrangement and division figures of the cells of root apex that root promeristem can be distinguished in two regions—a central cylinder or ‘core’ upon which the inverted cup-shaped meristem or ‘mantle’ is present. A few meristematic cells of the ‘core’ give rise to the stele, while the cup-shaped meristem forms the whole cortex, the outer epidermis, the columella and the side tissues of root-cap. Orientation of division figures are considered as the main evidence for zonation. The branching is dichotomous.
Roots are traversed by a monarch single eccentric stele. Around the vascular bundle the cortex disorganize and forms a “C”-shaped cavity—a characteristic feature of some of the fossil lycopods root.
As regards the arrangement of roots present study ofI. coromandelina confirms the early observations onI. japonica (West and Takeda, 1915).
pp 165-175 September 1963
Detailed pathological investigations on twelve pathogenic species ofPhyllosticta responsible for leaf-spot diseases were undertaken. Pycnidia of different organisms that developed over the leaves were viable for a sufficiently long time and they were capable of initiating the infection in the subsequent rainy season. The percentage of infected leaves increased during February–March. Availability of moisture to the inoculum was essential for initiating the infection during May and June. The pycnidia recovered from the plant debris and soil were also quite effective. The conidial viability of a particular pathogen varied on different hosts.
The author is grateful to Professor R. N. Tandon, Ph.D. (London), F.A.Sc., for the valuable suggestions and encouragement.
pp 176-185 September 1963