382 



continually taking place. This occurs by a kind of constriction- 

 process of the first germs ; one of the ends of these last being 

 pinched off, as it were, so that what was before a single body or 

 sac, becomes two, which are attached in a moniliform manner. 

 The new germs thus formed may consist each of a single cell 

 only, as I have often seen ; but they soon attain a more uniform 

 size by the endogenous formation of new cells within the sac in 

 which it is inclosed. In this way the germs are multiplied to a 

 considerable number, the nutritive material for their growth 

 being, apparently, a fatty liquid in which they are bathed, con- 

 tained in the abdomen, and which is thence derived from the 

 abdomen of the first parent. When these germs have reached 

 the size of about one three-hundredth of an inch in diameter, 

 there appears on each, near the inner pole, a yellowish, vitellus- 

 looking mass or spot, composed of yellowish cells, which, in size 

 and general aspect, are different from those constituting the germ 

 proper. This yellow mass increases after this iperiod^ pari jmssu 

 with the germ, and, at last, lies like a cloud over and partially 

 concealing one of its poles. I would, moreover, insist upon the 

 point that it does not gradually extend itself over the whole germ- 

 mass, and is, therefore, quite unlike a proligerous disc. 



When these egg-like germs have attained the size of one one- 

 hundred and fiftieth of an inch in diameter, there begins to 

 appear distinctly the sketching or marking out of the future 

 embryo. This sketching consists at first of delicately-marked 

 retreatings of the cells here and there ; but these last soon 

 become more prominent from sulcations, and, at last, the form 

 of an articulated embryo is quite apparent. 



During this time, the yellowish, vitellus-looking mass has not 

 changed its place, and although it has somewhat increased in 

 size, it appears otherwise the same. When the development has 

 proceeded a little further, and the embryo has assumed a pretty 

 definite form, the arches of the segments, which have hitherto 

 remained gapingly open, appear to close together on the dorsal 

 surface, inclosing the vitellus-looking mass within the abdomi- 

 nal cavity. It is this same vitelloid mass thus inclosed, which 

 furnishes the development of the new germs, (which, in this 

 case, would be those of the fourth colony, or D), and this germ 



