256 



PRODUCTION OF AMCEBOIDS IN VOLVOX. 



place in Volvox, tinrler circumstances that leave no reasonable 

 ground for that doubt of its reality which has been raised in regard 

 to the accounts of similar phenomena occurring elsewhere. The Endo- 

 chrome-mass of one of the ordinary cells increases to nearly double 

 its usual size ; but instead of undergoing duplicative subdivision so 

 as to produce a Macro-gonidium as in Fig. 109, b, it loses its colour 

 and its regularity of form, and becomes an irregular mass of colour- 

 less protoplasm containing a number of brown or reddish-brown 

 granules (a, a), and capable of altering its form by protruding or 

 retracting any portion of its membranous wall, exactly like a true 

 Amoeba. By this self-moving power, each of these bodies, c,c (of 

 which twenty may sometimes be counted within a single Volvox) 



Fig. 109. 



Formation of Amoeboid Bodies in Volvox : — a, a, ordinary cells 

 passing into the amoeboid condition ; b, ordinary macro-gonidium ; 

 c, c, free amceboids. 



glides independently over the inner surface of the sphere among its 

 unchanged green cells ; and bends itself round any one of these 

 with which it may come into contact, precisely after the manner of 

 an Amceba. After the Amoeboid has begun to travel, it is always 

 noticed that for every such moving body in the Volvox there is the 

 empty space of a missing cell ; and this confirms the belief founded 

 on observation of the gradational transition from the one condition 

 to the other, and on the difficulty of supposing that any such bodies 

 could have entered the sphere parasitically from without, that the 

 Amoeboid is really the product of the metamorphosis of a mass of 

 vegetable protoplasm. This metamorphosis may take place, ac- 

 cording to Dr. Hicks, even after the process of binary subdivision 



