During a cytotaxonomical study of a Kuwaiti diploid (2n = 26) population of Diplotaxis harra (Forssk.) Boiss (Brassicaceae), cytomixis and aneuploidy were found in 1.5% and 7.8% of the pollen mother cells (PMCs), respectively. Cytomictic cells revealed wide variability as far as the number of involved PMCs and their stage of division were concerned. The cytoplasmic channels, which were of different sizes, contained migrating chromosomes in a few cases. In some PMCs, the location of some of the chromosomes was clearly indicative of an imminent migration from a donor to its attached recipient cell. At metaphase I and anaphase I, PMCs showed variable degree of chromosomal transfer. In addition to a genetic control of the phenomenon, stress factors such as high temperature or drought in certain periods of the growing season may have contributed to the incidence of cytomixis in the material. A possible relationship between cytomixis and detected aneuploid PMCs, as well as a reconsideration of an evolutionary role of cytomixis is discussed.

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Khat (Cata edulis) is used among the natives of Yemen, Somalia, and southern Ethiopia for its stimulating effect as well as the psychological reaction induced among the users. Cata edulis, a shrub which resembles that of tea, was grown in terraced gardens in Arabia long before coffee was introduced. The leaves and buds of Cata edulis were said to contain an alkaloid similar to caffeine (Hill 1962). For this reason, the fresh leaves of khat are chewed by the people of Yemen, Somalia and southeastern Ethiopia. The addiction and cultivation of khat are still problems in Yemen and other Arab countries. The number of consumers is still high. The World Health Organization Commission on narcotic drugs decided in 1962 that the gravity of addiction could be measured by its effects on the community as a whole. It was also held that the social and economic effects of khat addiction could be measured by its effects on the community as a whole. It was also found that the social and economic effects of khat addiction were greater than its effect on the health of the individual. It was believed that the problem might be social rather than medical, but in some regions, a large proportion of the population was spending a great deal of the family income on khat rather than on food, with the consequence that the consumer and their families suffered from undernourishment and ill-health.It needs to be decided whether khat is 1) a narcotic drug producing ill effects comparable to those drugs under inter national control; 2) not a narcotic drug but with effect sufficiently harmful to justify limited control; or 3) completely harmless, not warranting any international action.It is due to this point and to the fact that khat has not yet attracted any investi gation in the field of cytology, that the idea arose to investigate the effect of khat extract on the process of mitosis and the structure of chromosomes, with the hope of determining whether or not khat is a harmful substance. Material and general methodsThe experimental plant in this investigation was used on bulbs of Allium cepa. Bulbs of Allium cepa were allowed to germinate in tap water. After the roots were 1-3cm long, they were placed in solutions which contained the test substances, for the treatment time given in the text. The root tips were then fixed in Carnoy 3:1 (absolute ethyl alcohol: glacial acetic acid) for 24 hours. Each series of experiments

Vicia faba was grown in crude oil polluted soil and its roots were extracted for the detection and estimation of hydrocarbons. Saturated and unsaturated Aliphatic Hydrocarbons (AHs) ranging from C(22) to C(36) were identified in AHs fraction. However, PAHs were not present in the same extract. This could be due to the fact that PAHs being toxic compounds are not accumulated in the plant root extracts of V. faba grown in crude oil polluted soil. Three phytoalexins were identified and estimated by mass spectrometric analysis in the root extracts of V. faba. These three compounds are 2-t-butyl-4-(dimethyl benzyl) phenol, 2, 4-bis (dimethyl benzyl) phenol and 2,4-bis (dimethyl benzyl)-6-butyl phenol. These phenolics in V. faba are being reported for the first time. These compounds are presumably elicited as a direct stress on crude oil hydrocarbons on the roots of this plant.