30 The Mycetozoa, and 



of the retreating veins, leaving a mass of the network after 

 the plasmodium has withdrawn." 



In other cases rejected matter, particles of starch or 

 spores of algse, or other things which have been taken up 

 by the plasmodium, are found thrown aside in the hollow 

 cavity of the foot of the sporangium, or even amongst the 

 contents of the sporangium itself. 



SPECIES. That true species exist in the myxies is doubted 

 by no one who has studied them, and the constancy of many 

 forms from distant places strongly supports this view. But it 

 may be permitted to doubt whether the range of variation 

 possible to one and the same species is yet sufficiently 

 known to enable us to rely with security upon the whole of 

 the present classification. In the progeny of a common 

 parent when under cultivation, great diversities have been 

 observed in the character of the calcareous walls of the 

 sporangium, in the thickness of the capillitium, and even 

 in its presence or absence, in the colour of the sporangium 

 walls, the capillitium, and even of the plasmodium. Until, 

 therefore, more species have been subjected to observations 

 under culture, or more life-histories have been exactly 

 traced, we must be prepared to regard the specific distinc- 

 tions as open to revision. Mr. Massie considers that he 

 has found cases of hybridism in myxies ; but this, perhaps, 

 requires confirmation. 



Whatever be the limits of variation within a species, the 

 great fact of specific distinction seems to admit of no 

 doubt, and one of the most interesting faculties of these 

 pieces of naked protoplasm is the power of knowing 



