PROTOPLASM 45 



not only constitutes differentiated films about the cell, the nucleus and 

 the plastids, but may also develop filamentous prolongations extending 

 from these films into the cytoplasm and from the tonoplast into the 

 vacuole. In extreme cases it may form a spongy framework throughout 

 the cytoplasm and a "medusoid" growth over the surface of the vacuole. 

 It appears to be the kinoplasm that is responsible for protoplasmic stream- 

 ing; it flows through the relatively stationary trophoplasm, carrying with 

 it the plastids and chondriosomes.^^ There appears to be an inverse 

 relationship between the abundance of chondriosomes and differentiated 

 kinoplasm; moreover, the active kinoplasm does not stain, but as it 

 metamorphoses into the tonoplast it colors faintly with Janus green. 

 These and other facts suggest that lecithin enters into the composition 

 of the kinoplasm and that the chondriosomes may represent a substance 

 used in its elaboration. 



Lloyd has shown that the contractile vacuole of the Spirogyra gamete 

 (see p. 228) arises by a swelling of kinoplasmic globules in the cytoplasm. 

 The cleavage of the protoplasm of many sporangia to form spores is also 

 regarded as an activity of extending kinoplasm. Such observations raise 

 a number of important cytological problems and emphasize the need for 

 further work along this line. 



Protoplasm and Metaplasm. — Because of the place they occupy in 

 cytological discussions we may outline several classifications of the sub- 

 stances composing organisms which certain writers have found useful. 



J. Hanstein (1868): 



1. Protoplasm: the living substance. 



2. Metaplasm: non-living substances in or on protoplasm. 

 M. Heidenhain (1902, 1907): 



1. Protoplasm: the principal form of living substance. 



2. Metaplasm: a less active form of living substance, formed by a process of 

 differentiation in protoplasm in connection with special functions, and capable of 

 growth, response to certain stimuli, and fui'ther differentiation. It is represented 

 chiefly by the intercellular substance of animals; also by certain other structures, 

 such as elastic and connective tissue fibrils. 



3. Non-living substances. 

 E. Rohde (1908, 1923): 



1. Protoplasm: the principal form of living substance. 



2. Metaplasm: a less active form of living substance; essentially the same as 

 Heidenhain's metaplasm but including also contractile and nerve fibers, which 

 Heidenham regarded as protoplasmic. Metaplasm, according to Rohde, cannot again 

 become protoplasm and does not continue from generation to generation. 



3. Non-living substances. 

 A. Meyer (1896, 1920): 



1. Protoplasm: the principal form of living substance. 



2. Alloplasm.: a less active form of living substance, essentially the same as the 

 metaplasm of Heidenhain and Rohde. Cilia, flagella, and cytoplasmic fibrils are 



'alloplasmatic organs." Organs of this class arise by direct transformation of all 



^1 Seifriz's cryptoplasm and phaneroplasm (p. 33) would both be included in the 

 kinoplasm. 



