524 7 HE BEGINNINGS OF LIFE. 



Actinophrys may, for some inexplicable reason, become 

 converted into Nematoids instead of Rotifers ^ Nay, 

 more, other specimens of Actinophrys, similarly derived 

 from the pangenesis of a Rotifer, may, by a slightly 

 more round-about process, also give rise to specimens 

 of the arachnidal Tardigrades 2. 



According to Dr. Gros, this latter transformation 

 takes place in the following manner : — A large specimen 

 of Actinophrys gradually becomes spheroidal, whilst it 

 retracts all its rays except one, by means of which the 

 mass continues anchored during its subsequent stages. 

 A succession of changes then takes place in its internal 

 substance, accompanied by the appearance and disap- 

 pearance of fatty-looking vesicles, whilst during this 

 time the external membrane becomes more and more 

 condensed and assumes an orange-brown colour. The 

 internal vesicular mass is gradually converted into an 

 active embryo, which in from fourteen to twenty-one 

 days ruptures its enveloping membrane and appears as 

 a large ciliated Planariole, visible by the naked eye. 

 This organism, after increasing in size and leading a 

 very active life for about ten days, gradually contracts 

 and finally becomes encysted 3, and the mass thus formed 



^ If a Nematoid and a Rotifer may come from two apparently similar 

 matrices, then the transformation of the Rotifer into the Nematoid, to 

 which we have previously alluded, is only a very little more startling 

 than the transformation of one form of Ciliated Infusorium into another, 

 or of a Ciliated Infusorium into a small Rotifer. 



2 Loc. cit., p. 438. 



2 See loc. cit„ p. 439 ; PI. N, figs. 1-6. 



