Volume 34, Issue 3
September 1951, pages 115-181
pp 115-147 September 1951
Regeneration by anterior and posterior substrates (having a single transection each), indicated presence along anteroposterior axis of three morphogenetic regions. (1) A region of unipotential capacity from 16/17 anteriorly, in which all morphologically determined regenerates were cephalic, with a section from 6/7 anteriorly in which regeneration was obtained only anteriorly. (2) A region of bipotential capacity in which morphologically determined regenerates were cephalic or caudal. Apparent directional limitations of bipotentiality enabled recognition of three sections: 17/18 to 22/23 (→ 27/28?) in which regenerates at anterior transections were all cephalic but at posterior transections were cephalic or caudal or cephalocaudal; a long middle section in which all anterior regenerates were cephalic and all posterior regenerates were caudal; a posterior section in which regenerates at anterior transections were cephalic or caudal or cephalocaudal but at posterior transections were all caudal, tentatively bounded by 176/177 and 200/201. (3) A region of unipotential capacity in which all morphologically determined regenerates were caudal. Experiments were not extended to permit recognition of a terminal section in which regeneration would only take place posteriorly.
The pattern of regenerative capacity thus indicated is complicated, inP. millardi, by induction of posterior heteromorphosis by a simultaneous anterior regeneration, with heteromorphic cephalic regeneration possible at least as far back as 88/89 and by various types of regulation. Induction of homomorphosis in a heteromorphic anterior regenerate. Induction of heteromorphosis in a homomorphic posterior regenerate. Induction of substrate orientation of nephridia in proximal segments of heteromorphic regenerates. Reorganization of substrate metameres into two or three segments with characteristics of regenerate metameres.
Structure of inhibited buds and cephalic monstrosities indicates brain ofP. millardi does not have an important role as an organizer in early stages of regenerative growth.
pp 148-156 September 1951
Adult beetles infest harvested bamboo culms within 24 hours of felling by boring in at the cut ends. Eggs, which are elongate, elliptical, 1·mm. long and 0·16 mm. broad, are inserted singly into the ends of the severed fibrovascular bundles. A female lays 29–52 eggs in 12–52 days depending on the food material on which it feeds. Incubation period averages 4 days. There are eight larval instars; the first one occupies 2 days and the others take 7–9 days each. The total larval period varies from 56–59 days. Pupal period is 3 days and the pre-emergence period 3–7 days. From egg to the emergence of adult it occupies 60–63 days. There are three distinct generations in a year.
pp 157-164 September 1951
pp 165-171 September 1951
The time interval between the various stages commencing with the appearance of flag-leaf of the boot to complete anthesis of panicle inD. annulatum, D. caricosum andB. intermedia was studied. Detailed study of blooming of florets and dehiscence of anthers ofD. annulatum was also carried out.
InD. annulatum andD. caricosum a period of two days elapses between complete emergence of panicles out of the boots and the commencement of anthesis thus allowing sufficient time to self and treat number of panicles at a time. InB. intermedia anthesis and dehiscence take place as the panicles emerge out of the boots and thus it is necessary to bag or treat the panicles immediately three or four days after the appearance of flag-leaf.
A period of 11 days inD. annulatum andD. caricosum and 9 days inB. intermedia is required from the appearance of flag leaf to completion of anthesis.
InD. annulatum anthesis and dehiscence take place as a rule, during night and early morning between 9p.m. and 4a.m.
InB. intermedia anthesis of florets and emergence of the panicles out of the boots take place simultaneously bit by bit and takes about 4 days for completion of these two processes. Blooming and dehiscence, however, take place during night and early morning as inD. annulatum.
D. annulatum, D. caricosum andB. intermedia appear to behave as self-pollinated grass species.
Laboratory experiments showed thatD. caricosum blooms and dehisces during night and early morning at about the same time asD. annulatum.
pp 172-181 September 1951