v.] METAMORPHOSES OF INSECTS. 101 



This completes their life history as observed by 

 Haeckel, who found it easy to retain them in his 

 glasses in perfect health, and who watched them 

 closely. 



As another illustration I may take the Magosphcera 

 planula, discovered by Haeckel on the coast of 

 Norway. 



In one stage of its existence (PI. 5, Fig. 10) it is a 

 minute mass of gelatinous matter, which continually 

 alters its form, moves about, feeds, and in fact behaves 

 altogether like the Amoeba just described. It does 

 not, however, remain always in this condition. After 

 a while it contracts into a spherical form (PL 5, Fig. 

 11), and secretes round itself a structureless envelope, 

 which, with the nucleus, gives it a very close resem- 

 blance to a minute egg. 



Gradually the nucleus divides, and the protoplasm 

 also separates into two spherules (PI. 5, Fig. 12) ; these 

 two subdivide into four (PL 5, Fig. 13), and so on 

 (PL 5, Fig 14), until at length thirty-two are present, 

 compressed into a more or less polygonal form (PL 5, 

 Fig. 15). Here this process ends. The separate 

 spherules now begin to lose their smooth outline, to 

 throw out processes, and to show amceboid move- 

 ments like those of the creatures just described. The 

 processes or pseudopods grow gradually longer, thinner, 

 and more pointed. Their movements become more 

 active, until at length they take the form of ciliae 

 The spherical Magosphsera, the upper surface of 

 which has thus become covered with cilise, now begins 

 to rotate within the cyst or envelope, which at length 

 gives way and sets free the contained sphere, which 



