4 DR. J. E. T. AITCHISON ON THE BOTANY OF 
were some large bushes of Lycium barbarum, almost devoid of foliage, but covered with 
bright red fruit, very like small capsicums. Неге we lost several camels from no known 
cause, though all those found dead were lying near these bushes, and had been eating 
greedily of the berries. I opened several camels, but the post-mortem showed no 
symptoms of irritant poisoning, yet there was nothing I could detect in their paunches 
except the berries. From the camels having died so suddenly I suspected narcotic 
poisoning, and yet a Lycium, although nearly allied to a poisonous genus, is not sup- 
posed to be itself poisonous. І carefully examined the whole country round, and there 
was nothing else they could have eaten of a poisonous nature. The natives declared 
the Lyciwm was not poisonous, and subsequently I often saw camels browsing on this 
shrub without any ultimate evil effects. 
In some localities the sand-dunes were covered with Huphorbia cheirolepis; a very 
elegant species, which still, late though the season was, maintained its green foliage. 
Tribulus alatus covered the tops of the sand-dunes in many places with a sward. Cyperus 
pungens at this season only existed in numerous leafy tufts, and very little of the 
fruiting heads were obtained, though sufficient for identification. Convolvulus erinaceus 
was not uncommon. Peculiar-looking balls formed of a prickly fruited shrub, Agro- 
phyllum latifolium, with few or no leaves were noticed rolling about, driven by the 
winds hither and thither over the flat clay plains (or Pat), occasionally accumulating into 
heaps. This shrub grows in loose sand, and as it is very leafy it is easily lifted out of 
its position by the wind and, being driven about, it takes the form of a ball, which is 
often increased in size by coming in contact with other similar plants. It was soon 
dubbed “the wanderer;" the natives call it the ‘spinning-wheel,” in allusion to this 
peculiarity. It was curious to note the condition of the roots of the plants that live in 
these beds of pure sand; some, like the Наюхуоп, thrust their roots so deeply into the 
sand as to anchor themselves in the solid ground beneath ; others, like Huphorbia, with 
slight stems, little affected by the wind, do not require to be so firmly fixed, and do not 
root so deeply; grasses and sedges have their fibrous roots greatly lengthened, and 
develop a spongy tissue as thick as a goose-quill. "These spongy enlargements serve 
two purposes, one for holding fluid for future requirements, and the other for maintaining 
the position of the plants, each root acting as an individual anchor. The same plants 
not growing in this loose sand did not possess this peculiar development of their roots. 
Indeed all the plants that occupy these sandy dunes have a hard struggle for existence ; 
not only have they much to do to keep themselves in position on account of the wind, 
but when sand is heaped upon them they have to learn to keep themselves alive under 
the superimposed weight and at the same time to fight their way through it. Further- 
more the sand blown on them during summer is hot and dry, so hot and dry that unless 
these plants are capable of collecting and maintaining a supply of moisture, they must 
inevitably perish from drought. Оп other occasions their surrounding medium may 
be suddenly removed by wind, leaving them to be blown about with the chance of 
being utterly destroyed before they can be again partially covered with sand and thus 
afforded the means for supporting life. 
In stream-beds amongst thickets of Tamarisk, where there were perennial streams, 
