558 THE MICROSCOPE. 



is deposited previous to boiling. A pint of the fluid 

 contains about a quarter of a j)ound of salt, and this con- 

 centrated solution destroys most other marine animals." 

 During the fine days in summer Ai^temice may be observed 

 in immense numbers near the surface of the water, and, as 

 they are frequently of a lively red colour, the water appears 

 tinged with the same hue.^ There is nothing more elegant 

 than the form of this little "animal. Its movements are 

 peculiar. It sv»^ims almost always on its back, and by means 

 of its tail it runs in all directions, its feet being in constant 

 motion. They are both oviparous and ovo viviparous, accord- 

 ing to the season of the year. At certain periods they only 

 lay eggs, while during the hot summer months they pro- 

 duce their young alive. In about fifteen days the eggs are 

 expelled in numbers varying from 50 to 150. As is the 

 case with many of the Entomostraca, the young present a 

 very difl'erent appearance from the adult animals ; and 

 they are so exactly like the young ot Ghirocephalus, that with 

 difficulty they can be distinguished the one from the other. 

 The ova of other species are furnished with thick cap- 

 sules, and imbedded in a dark opaque substance, j)resenting 

 a minutely cellular appearance, and occupying the inter- 

 space between the body of the animal and the back of the 

 shell. This is called the ephippium.- The shell is often 

 beautifully transparent, sometimes spotted with pigment : 

 it consists of a substance known as chitine, impregnated 

 with a variable amount of carbonate of lime, which pro- 

 duces a copious efi'ervescence on the addition of a small 

 quantity of acid, aiid when boiled it turns red, like the 

 lobster. Their shells vary in structure. Sometimes they 

 consist of two valves united at the back, and resembling 



(1) It is a curious fact that salt-water wlien highly concentrated frequently 

 assumes a red colour, audthat this sliould have been attributed to the presence 

 of the Artemiu salina, as in the case of fresh-water noticed elsewhere found 

 coloured red by a species of Parmnaxmm. The cause of this red colour, which 

 was well known to take place in the salt marshes and reservoirs of salt-water 

 at Montpellier, was made the subject of a very gi-ave discussion in France. 

 Some maintained that the colour Avas caused by the presence of Artcmiai, while 

 others declared that it arose from vegetable matter, either Hamatococcus or 

 Fratococcus. M. Joly, came to the conclusion, after many careful examinations, 

 that the red colour depends upon the presence of myriads of monads, and that 

 the Artnnice living upon these partook of the same red hue, and thus the water 

 aiJiicared to be of the same colour. 



(2) See paper on " lleproduction iu Da^Jinia," by Sir John Lubbock, Philos. 

 Trans. 1857, p. 79. 



