228 



KNOWLEDGE. 



June. loil. 



enables them to survive being dried. In this 

 condition the eggs may be carried long distances in 

 mud. adhering to the feet of wading birds, or may 

 be blown about by the wind, and the distribution of 

 the species from one localit\' to others is thus 

 rendered possible. Sometimes, however, the Brine 

 Shrimp is viviparous, the eggs hatching while 

 still within the brood-sac. and before the shell has 

 been completely formed. In either case, the \-oung 

 appear first in the form of tiny si.x-legged lar\ae 

 with an oval unsegmented bod\- and a single eve. 

 This type of larva, known as a imiiplitis, is found in 

 many other groups of Crustacea, such as Copepods. 

 Barnacles, and some of the true Prawns, which 

 in the adult state are very different from the Brine 

 Shrimp. In the course of development the bod\- 

 elongates and becomes di\'ided into segments, the 

 eleven pairs of swimming feet successively appear, 

 the stalked eyes grow out at the sides of the head, 

 the three pairs of nauplius limbs lose their 

 swimming branches and become the antennules, 

 antennae, and mandibles, and the animal graduallv 

 acquires the form and structure of the adult. 



The great variability of the Brine Shrimp, alreadv 

 alluded to, seems to be correlated with the \ar\ing 

 chemical composition antl concentration of the 

 solutions in which it li\es. It lias been found in 

 water containing no less than _'7 per cent, nf 

 dissolved salts, while on the other band it sometimes, 

 though rarely, occurs in water that is quite fresh. 

 In Central Asia, Brine Shrimps ha\-e been found 

 living in lakes containing so much sodium carbonate 

 that the water had a distinctly "soapy" feel. A 

 Russian naturalist, Schmankewitsch, showed, many 

 years ago, that it was possible, by breeding Artemia 

 in solutions of varying concentration, to produce 

 changes of form, especially in the end-lobes of the tail. 

 Some of the characters thus produced had pre\-iouslv 

 been regarded as distinctive of separate species, but 

 there is no ground for the statement sometimes made 

 that the e.xperiments resulted in changing one species 

 into another. They simiily showed that the species 



had been mistakenly separated on variable and 

 untrustworthy characters. The statement that some 

 of the specimens assumed the characters of the 

 allied but (juite distinct genus Branchipiis has since 

 been shown to be erroneous. 



The manufacture of salt from sea-water in the 

 way described above has long since ceased in this 

 countr}-, though it is still carried on on the shores of 

 the Mediterrannean, and it is probably many years 

 since the Brine Shrimp became extinct as a member 

 of the British fauna. An accidental observation 

 recently made at the Natural History Museum 

 shows, however, that it is probabK' a ver\- simple 

 matter for anyone to obtain a supply of living 

 specimens. A solution of " Tidman's Sea Salt." 

 which had been set aside and forgotten, was found 

 after some weeks to have about a dozen full-grown 

 Brine Shrimps activel}- swimming about in it. All 

 of these were females and carried egg-pouches full 

 o( eggs, which were deposited shortly afterwards and 

 in a few days the larvae of a second generation were 

 hatched from them. .\ fresh packet of the salt was 

 then experimented with. About eight ounces were 

 dissolved in five pints of tap water, and microscopic 

 examination of the sediment showed that it 

 contamed numerous eggs. In about four da\'s a 

 swarm of nauplius larvae issued from these, and 

 in the course of a fortnight thev were well on 

 the way to assume the adult form, although still 

 \ery small. 



It is impossible, without further trial, to say 

 whether eggs capable of development are always 

 present in Tidman's Sea Salt. The\' cannot retain 

 their vitality indefinitelw and, in fact, a \'ery old 

 sample of the salt found among the Museum stores 

 proved to be barren of lite. It need hardh' be said 

 that salt which in the course of manufacture has 

 been exposed to artificial heat, would contain no 

 living eggs. In repl\- to an inquir\- on this point 

 Messrs. Tidman & Son kindly stated that their 

 Sea Salt is manufactured abroad from sea-water 

 evaporated b\- the sun"s heat. 



NOTICE. 



THE SOUTH AFRICAN JOURNAL Ol- SCIENCE. 



— In the April issue of tlie Soiifli African Juiirnal of 

 Science appear notes on Croialaria Burkcana and other 

 leguminous plants causing disease in stock. Beasts eating 

 Crotalaria develop laminitis within a few days, their hoofs 

 grow long and, unless attended to, the beasts get so stiff in the 

 joints that they lie down and are unable to rise again. Goats 

 seem to be immune and it is curious to note that the same 

 fact is recorded in the case of Cytisus proliferus m the 

 Canary Islands. This Cro?a/rt)-((7 is recorded from the Trans- 

 vaal, Orange Free State, the Cape Province and Natal and 

 there is one record from Zululand. It is most common on sandy 

 soils and it is found that even if it exists in the unbroUen veld 

 in such small quantity as to be harmless, as soon as the land 

 is cultivated and maize or kaflir corn planted, the Crotalaria 

 makes its appearance along with them. The plant is said 

 to be most poisonous when the pods, called 1>\ the Boers 

 " Klappers," have developed. In the Eastern and Central 

 United StateaCrotalaria sagitfalis or " Kattle-box" produces 

 a stock disease called " Crotalisni " or "Missouri bottom 

 disease," which is more frciiaentl\- fatal than tliat induced 



by the South African lliirl;cana. Other species oi Crotalaria 

 in Australia arc known to be injurious to stock. The notes 

 also record the effect of Lcssertia, Melolohinni and Cytisns, 

 in Africa ; Swainsona galeiiifolia (Darling pea or indigo) in 

 Australia; Astragalus, Oxytropis and Sophora, in America. 

 In the same number Ur. P. D. Hahn describes a geyser in 

 Rhodesia, the only one that has been discovered in that 

 country. The geyser is situated near Fulunka's Kraal, 

 about two miles south of the Zambesi River and forty miles 

 below the confluence of the Gwai River. It issues from a 

 round hole, about two inches in diameter, in solid sandstone 

 and throws up a continuous stream of water eight feet high. 

 The temperature of the water is slightly below boiling point ; 

 the force with which the water is expelled is not great, as the 

 geyser can be easily plugged with a stick, while a ten pound 

 stone placed over the aperture will stop the play of water. 

 Analysis shows the silica content of the water to be 13-65 

 grains per gallon. The water of ordinary springs, either deep- 

 seated or surface, rarely contains so much as one grain of 

 silica per gallon, while the Iceland geysers show from eleven 

 to thirt\'-fi\e grains. 



