OYITOSITION AND THE CONSTITUTION OF THE EGG. 



219 



The nests are found in the damp earth, under stones, the bark of 

 trees, etc. The eggs within them may be glued together into large 

 clumps (Jul as). The Polyxenidae surround the heaps of eggs with 

 a thick envelope formed from their own hair. Glomeris lays its 

 eggs singly and at wide intervals ; each egg is surrounded by the 

 female with a special capsule formed out of earth moistened by a 

 glandular secretion.* 



It has been stated that viviparous forms occur among the Scolo- 

 pendridae ; but, on the other hand, some of these animals have 

 also been observed to lay eggs in large clusters. In these latter 

 cases it was found that the eggs are taken care of by the female, 



Fig. 106. — Sections through eggs of Geophilus ferrugineus at two early stages, illustrating the 

 formation of the blastoderm (after Sograff). d, yolk ; dp, yolk-pyramids ; 7.-, nuclei, each 

 surrounded with a protoplasmic area. 



which rolls itself spirally round them and remains immovable until 

 the young are hatched. Lithobius lays its sticky eggs one at a time 

 and rolls them in the soil until they become coated with earth. 



The eggs, which are usually spherical, seldom oval, are very rich 

 in yolk. They are surrounded by a vitelline membrane and another 

 structureless but firmer envelope, the chorion, which is apparently 

 secreted by the genital ducts. 



* Statements of a more detailed nature as to the time and mode of laying 

 the eggs in the Diplopoda are to be found in the older works of NEWPORT and 

 Fabue, and more especially in two treatises by 0. v. Rath (Xos. 16 and 17). 

 Further accounts of the laying of the eggs and the care of the brood are given 

 by Latzel (Xo. 10) in his description of different species of Myriopoda. 



