METAMORPHOSES OF INSECTS. 



103 



minal vesicle ; it increases in size, and after a while 

 the yolk and the germinal vesicle divide into two 

 (Fig. 61), then into four (Fig. 62), and so on, just as 

 we have seen to be the case in Magosphaera. From 

 the minute cells (Fig. 63) arising through this process 

 of yolk-segmentation, the body of the Tardigrade is 

 then built up. 1 



.FiG. 60, Egg of Tardigrade, Kaufmann, Zeit. f. Wi<=s Zool. 1851, PI. i. 61, Egg 

 of Tardigrade after the yolk has subdivided. 62, Egg of Tardigrade in the 

 next stage. 63, Egg of Tardigrade more advanced. 



Though I will not now attempt to point out the full 

 bearing of these facts on the study of embryology 

 generally, yet I cannot resist calling attention to the 

 similarity of the development of Magosphaera with 

 the first stages of development of other animals, 

 because it appears to me to possess a significance, the 

 importance of which it would be difficult to over- 

 estimate. 



Among the Zoophytes Prof. Allman thus describes 2 

 the process in Laomedea, as representing the Hydroids 

 (PL 6, Fig. i, represents the young egg) : "The first 

 step observable in the segmentation-process is the 



1 It is true that among the Insecta generally the first stages of de- 

 velopment differ in appearance considerably from those above described; 

 those of Platygaster, as figured by Ganin (ante Figs. 17-22), being 

 very exceptional. 



' 2 Monograph of the Gymnoblastic or Tubularian Hydroids, by G. J. 

 Allman, Ray Soc. 1871, p. 86. 



