The structure of undischarged and discharged trichocysts has been examined in Paramecium caudatum, and their light-microscopic appearance compared with their fine-structural organization. In living specimens undischarged trichocysts appear to be of a single type with a unimodal variation in length about a mean of 37 fim. When fixed for electron microscopy or compressed beneath a coverslip many ...

Details of the life cycle of Aneugmenus merida Smith (Hymenoptera: Tenthredinidae) reared under laboratory conditions are reported. Females may produce parthenogenetic or non-parthenogenetic eggs. After eclosion, males of A. merida go through five larval instars, pre-pupa, pupa and imago. The complete life cycle lasts approximately 44 days. Larvae feed on bracken [Pteridium caudatum (L.) and Pt...

Cells of Paramecium caudatum in the immaturity period of the life cycle contain substances which repress the expression of mating ability when introduced into mature cells. When 5 x 10 /tm of immature cytoplasm were injected into mature cells, loss of mating ability occurred and it continued for more than 15 fissions after the injection. The effective substances are contained in the soluble fra...

(Prom the School of Tropical Medicine, Calcutta) In a previous paper it was observed by one ? us (Basu and Bose, 1941) that although the toxicity (LD/50) of 2-chloro-7-methoxy-5 (8c lethyl-amino-butyl) amino-acridine, in mice, Jas only slightly higher than that of 2-chloro~n}ethoxy-5 (8-diethyl-amino-iso-amyl) aminoacndine, the toxic effect of the former on cultures of Paramecium caudatum was f...

Binding of (45)Ca by live Paramecium caudatum was determined under various external ionic conditions. It was found that calcium uptake was separable into at least two components, a rapid and a slow one. The rapid component was influenced by the presence of certain other ions in a manner which agrees with the law of mass action. It appears that an ion exchange system may be involved in a binding...

BACKGROUND Ectothermic organisms are thought to be severely affected by global warming since their physiological performance is directly dependent on temperature. Latitudinal and temporal variations in mean temperatures force ectotherms to adapt to these complex environmental conditions. Studies investigating current patterns of thermal adaptation among populations of different latitudes allow ...

Stimulus generalization to different levels of illumination in Paramecium caudatum" (2008). Theses and Dissertations. Paper 1190. This study was conducted to determine if paramecia (P. caudatum), unicellular organisms, could exhibit stimulus generalization as do mammals and other multicellular organisms. Paramecia were placed in a trough that was divided into two equal portions, one light and o...

Direct evidence is presented in support of the widely held idea that membrane-bounded vesicles can bind firmly to microtubules. This is shown in P. caudatum which contains ribbons of straight microtubules located in open cytoplasm and uniquely associated with the disk-shaped vesicles. These vesicles frequently lie flat against the face of the ribbons at a constant distance of 30-40 nm. Under ce...