Volume 55, Issue 5
May 1962, pages 213-284
pp 213-223 May 1962
1. Light is not essential for the formation of stipes from sclerotia, which can be formed in total darkness, but no apothecia can develop from them in the absence of light.
2. A daily photo-period of 12 hours is quite adequate for the normal development of apothecia.
3. As regards the quality of light, white is the best and green and red lights are very poor and blue light is the worst.
4. Constant illumination is not harmful.
5. An intensity of illumination amounting to 12 to 14 foot-candles appears to be quite adequate.
6. Adequate aeration is extremely important for the development of normal apothecia.
7. Burial of sclerotia, whatever its depth, is deleterious to apothecial formation, which is best only on the surface of the substratum.
8. Sclerotia do not germinate and form stipes unless they are in actual contact with water. Contact with free water, however, must be partial and not such as to completely submerge them, in which case only stipes and no apothecia are produced.
pp 224-232 May 1962
The distribution of the different varieties ofPtychodera flava on the east coast of South India is described, along with an account of the five varieties of this species occurring in the different regions of the Krusadai group of Islands in the Gulf of Mannar.
An examination of the surface currents in the Bay of Bengal and the Indo-Pacific region of the Indian Ocean, during the breeding season ofPtychodera flava (when its larvæ are in the plankton) suggests the probable course of distribution of the species, from a starting point near about the Maldive and Laccadive archipelago.
pp 233-238 May 1962
1. One hundred and nine new host plants attacked by the species ofStriga andSopubia have been recorded. Seventy-two of these are for the three species ofStriga, viz., S. lutea, S. densiflora andS. euphrasoides and 37 forSopubia delphinifolia, G. Don.
2. ParasiteStriga was observed for the first time on the host plants belonging to familiesCapparidaceaœ, Verbenaceæ, Labiatœ andAcanthaceœ.
pp 239-243 May 1962
The sclereids found in the stem, leaf, perianth and fruits of this species correspond to the category of astrosclereids. Their ontogeny reveals that they are transformed cells of the mesophyll. An interesting feature is the presence of crystals in the adult sclereids.
pp 244-250 May 1962
1. The temperature employed to produce sclerotia affects their reproductive capacity to a surprising degree. Sclerotia produced at 15° C. and lower do not produce apothecia. The best development of vigorous and well-developed apothecia takes place in the case of sclerotia produced at 25° C.
2. Sclerotia germinate over a wide temperature-range of 5–25° C., but at temperatures below 15° C. and above 20° C., their germination is almost totally restricted to the formation of stipes, which remain abortive. The optimum temperature-range for apothecia formation is 15–20° C.
3. Freezing of sclerotia at a very low temperature, like − 15° C., or burying them under snow during winter months does not kill them, but destroys their reproductive capacity. Chilling of sclerotia at 0° C. for a week, on the other hand, hastens the formation of apothecia from them.
pp 251-255 May 1962
pp 256-262 May 1962
A detailed account of the microscopical structure of the lateral line organs is given. The lateral line system is very superficial inOphiocephalus being dorsal to the scales and devoid of pore canals. The end-organ is similar to those of other fishes described. The structure of the sense cells and their hollow sac-like arrangement is very similar to the structure of organs capable of perceiving sound vibrations in other vertebrates as well as a few invertebrates.
pp 263-275 May 1962
A critical examination of the periodic markings on otoliths has helped to establish that the markings could be used for the estimation of age and growth ofA. nebulosa. The relationship between the otolith radius and total length of the fish has been determined, based on which a formula for back calculation of lengths at different ages is derived. A study of the otolith margins has shown that the formation of the translucent bands is annual in nature. A von Bertalanffy growth equation has been fitted to the data and it is found that, in the size ranges studied, this growth equation adequately describes the pattern of growth of the eel. Earlier studies on the age and growth of the eel are discussed and a comparison with growth of other species of eels of the same genus has been attempted.
pp 276-284 May 1962
The structure of the mitotic chromosomes ofAllium cepa has been elucidated by controlling the temperature and time of exposure of fresh roots to stain fixatives. The details seen in material stained in N HCl-orcein for 8 min. at 60° C. and squashed after varying intervals of storage at room temperature were essentially similar to pictures obtained with 1% aceto-orcein and 1% aceto-orcein-N HCl (10:1) under identical conditions of handling. The chromosomes appear quadri-partite at metaphase and bi-partite at anaphase. A rare instance of the precocious assumption of a quadri-partite condition by two anaphase chromosomes is illustrated. Caduceus coiling of chromonemata was seen in chromosome bridges also. Chromosomes have material easily dissociable from the chromonemata and their removal does not affect the structural integrity of the chromosome.