134 M. straus-durckheim's 



intestinal canal near the anus. These are the urinary vessels, 

 and they have sometimes, near their insertion, a reservoir, 

 w*hich performs the functions of a bladder. In all insects we 

 find at least one kind of these glands, inserted sometimes 

 above, sometimes below the gizzard. From the experiments 

 of M. Rengger, it appears that these organs are urinary 

 organs. The analysis of their contents confirms this, they 

 being composed of ammonia, potass, and uric acid, existing 

 probably in the form of a suburate of potass and ammonia. 



Part IV. — Generation. 



In the Myriapoda, Arachnida, and in Insects, the sexes 

 are invariably separate ; and it appears doubtful whether any 

 of the Crustacea are really hermaphrodites, though as yet no 

 individuals of some genera, as Cypris and Apus, have been 

 found unfurnished with eggs. In the Annelida, most of the 

 genera are imperfectly hermaphrodite. In Crustacea and 

 Insects we find some species which, though not hermaphro- 

 dites, are capable of producing young without fecundation for 

 several generations. Jurine observed that the Crustaceous 

 genus, Daphnia, possessed this faculty to the sixth generation. 

 The first genus of Insects in which this power was observed, 

 is Aphis, and here it is very striking. Mr. Coulter, an Irish 

 naturalist, relates, that Smerinthus Populi can produce several 

 generations without fecundation. e 



All the Annulosa, and most of the Annelida, are exclusively 

 oviparous, or ovo- viviparous ; but some of the latter, as Nais, 

 &c, besides being oviparous, multiply almost after the manner 

 of the Zoophytes, the posterior part separating, and becoming 

 a perfect individual. 



Here we may notice the power possessed by some animals, of 

 renewing parts of their bodies which may have been broken oflf. 

 In Insects and the Scolopendrce this never takes place; and, 

 moreover, a simple wound never heals, it only dries over. In 

 Crustacea and Arachnida, the feet are capable of being re- 

 produced exactly in their original form. But does this faculty 



e Who is Mr. Coulter .' and will he favour the world with some further 

 particulars with regard to this extraordinary fact, which M. Straus relates on 

 the authority of a statement made by Mr. C. to him ? 



