46 MORPHOLOGY AND CULTURE OF MICROORGANISMS 



Metachromatic corpuscles appear not only in the vacuoles, but also 

 in the perivacuolar cytoplasm. There they spring up, to diffuse finally 

 in the vacuole where they increase. It is difficult to observe their 

 manner of forming in the mycelial filaments, but in the preparation for 

 sporulation in some molds (asci of the higher Ascomycetes), it has 

 recently been demonstrated that they start in the midst of the elements 

 of the chondrium, which act as plastids similar to the plastids of the 

 higher plants. They start in the interior of the granular-mitochondria 

 or in the rod-mitochondria (Fig. 31). In the former case, a small cor- 



-s. 



FIG. 31. Formation of metachromatic corpuscles in a cell of the perithecium of 

 Pestularia vesiculosa. The rod-mitochondria form, on their crossings, vesicles (c) 

 consisting of a metachromatic corpuscle unstained by the special method which 

 served to differentiate the chondrium. Some corpuscles (a), more highly developed, 

 are found in the vacuoles still surrounded by their mitochondrial shell; others (c) 

 at the completion of their development have worn through their mitochondrial 

 covering. 



puscle appears in the substance of a mitochondrium, then develops 

 gradually, while the mitochondrial membrane which envelops it grows 

 thinner; is reduced to a small capping of the grain on one side; then 

 disappears when the latter reaches maturity. It is noteworthy that the 

 corpuscles emigrate with their plastid to the interior of the vacuoles 

 during their development. 



When the corpuscles start in a rod-mitochondrium the process is 

 much the same as in the granular-mitochondria; when several rod- 

 mitochondria are involved, at their junction small corpuscles are 

 seen to form; the parts of the rod-mitochondria which join are then 

 absorbed and the corpuscles, enclosed in their mitochondrial membrane, 

 once separated, undergo the same evolution as above. 



Thus the metachromatic corpuscles, like grains of starch in the 

 higher plants, start in the midst of the mitochondria and develop 

 gradually out of their mitochondrial matrix with the aid of the vacuolar 

 substance. 



