Remarkable Points in Life-History of Phyllopods. 6_ 



water Arteuiia into Brancliipus stag7ialis L the species apparently 

 which Mr. Halkett described. Arteniia differs Httle from Bran- 

 cJiipus in general form, though the former has eight segments in 

 the posterior part of the body while Branchiptis has nine. Verril, 

 it is true, has disputed this and has maintained that the only 

 reliable feature of distinction is the pair of prehensile organs -at 

 the anterior end of the body in the male. Apart from disputes 

 as to details, the fact is generally accepted that the greater or 

 less saltness of the water determines, in the most marked manner, 

 the form and structure of these creatures. Naturalists are fully 

 aware of the potency of changed external conditions in modifying 

 the characteristic features of animals, hwt \{ Arteinia salina, as 

 Schmankcwitsch claims, can be transformed into not only 

 a different species of the same genus, Arteniia inilhausenii \ but 

 more, that it can be changed into Brmichipus stagnalis, a species 

 of a different genus, by gradually adding fre.sh-water to salt- 

 water, the experiment is one of the most momentous character. 

 Hardly less interesting is the fact that the eggs of these 

 Phyllopods can endure the utmost variations of temperature, 

 moisture, and dryness. Mr. Halkett describes the eggs as dark 

 bodies like small pellets, enclosed in a pouch behind the gill- 

 feet. They appear to escape from this pouch and remain un- 

 harmed through conditions of the most trying and perilous 

 nature. Some Phyllopod eggs will not, indeed, hatch out unless 

 subjected to extreme dessication, of which the ova oi Apus are 

 an example ; but the ^^^s of Braiichipus survive equally well 

 whether they have been kept in perfectly dry or in moist mud. 

 Of course the albumen is so difficult to dry that it may be 

 subjected to extreme dessication without really becoming dry. 

 In fact it is this feature in the albumen of eggs, which explains 

 some of the supposed marvellous cases of Infusorians, Rotifers, 

 and the like, which are stated to have revived after thorough and 

 prolonged dessication. Pouchet has shown that the animals 

 really died, but their eggs survived, and on being moistened, 

 hatched out. The new generation were thus mistaken for the 

 supposed resuscitated parents. The eggs of many Phyllopods 



