EARLY DEVELOPMENT OF JULUS TERRESTRIS. 233 



out on the same species as Newport^s, confirm his account. 

 In my opinion the conclusion to be drawn from these diflferent 

 accounts is that in different species of Chilognatha, and even in 

 closely allied species of Julidse, the hatching of the embryo 

 takes place at very different stages of development. 



In 1841, Newport published his paper on the organs of 

 reproduction and the development of the Myriapoda (11). 

 This is the first paper containing any real information of the 

 early stages in the development. On the first three days he 

 describes the appearance of the yolk-spherules as seen through 

 the chorion, and describes the whole contents of the egg as 

 becoming firmer. On the fourth day he saw " a little granular 

 mass on one side of the shell " which he was inclined to regard 

 as the future being. He made no further observations till the 

 nineteenth day, when he describes the ventral flexure of the 

 embryo within the shell. On the twentieth day he was able 

 to make out six body segments. On the twenty-fifth day the 

 embryo was hatched. 



I am inclined to think that the little granular mass which he 

 describes on the fourth day was the first beginning of the blas- 

 toderm. 



Nothing more was written on the early development of the 

 Myriapoda till 1874, when Metschnikoff published his paper 

 (9), which contains the greater part of what we know of 

 Chilognath development. His fullest observations were made 

 on Strongylosoma. He describes the segmentation, the forma- 

 tion of the blastoderm, the formation of the ventral plate, 

 the ventral flexure of the embryo, the segmentation of the 

 mesoblast, and of the body, and gives a full description of the 

 later stages. As I shall have to discuss his paper in detail I 

 will not attempt to give a fuller account of it here. 



In 1877, Stecker published a paper (13) in which he describes 

 the development of Julus fasciatus and several other species 

 of Chilognatha. His account does not agree either with mine or 

 with that of Metschnikoff. As his account has been fully 

 criticised by Balfour (2), I will not refer to it here at greater 

 length. 



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