44 



INTRODUCTION TO CYTOLOGY 



representing fused rows of cilia, and undulating membranes, which are 

 mainly sheet-like extensions of the ectoplasm (Fig. 20, A), are all essen- 

 tially ectoplasmic organs. In Blepharisma, Chambers and Dawson find 

 that when touched with a needle the undulating membrane breaks up 

 into cilia, which may reunite. A further motor differentiation is seen in 

 the minute contractile fibrils known as myonemes (Fig. 20, B), which are 

 analogous to a system of muscle fibers. In ciliated forms they run 

 beneath the rows of cilia. 



Contractile or pulsating vacuoles sometimes appear to originate in the 

 ectoplasm, although they may later lie much deeper. In certain cases 

 definite actively protective organs, the trichocysts, are differentiated in the 

 ectoplasm. A sensory function may be performed by the "eyespot, " 



A B CDS F 



Fig. 20. — Types of motile apparatus. A, Trypanosoma tincce, showing undulating 

 membrane. B, Trypanosoma percw, showing myonemes. C, velar cilia of ^olis. D, 

 Uroglena volvox. E, Phacus pyrum. F, Hamatococcus pluvialis. {A and B after Minchin; 

 C after G. Carter (1926) ; D F after J. B. Petersen, 1929.) 



which in some cases appears to be ectoplasmic in origin (see p. 67), and 

 also by flagella and cilia, which are often receptors of tactile stimuli. 



Kinoplasm. — In his descriptions of the plant protoplast Strasburger 

 (1892, 1897a, 1898) made a distinction between the nutritive alveolar 

 trophoplasm and a specialized active kinoplasm, the latter constituting 

 the plasma membrane, fibrils of the mitotic figure, centrosomes, and the 

 contractile substance of cilia and allied structures. -^ Although the theo- 

 retical aspects of such a distinction were overemphasized by certain 

 writers, the terms have remained useful for descriptive purposes. 



The importance of kinoplasm has been emphasized anew by Lloyd 



and Scarth^" in studies of living cells of Spirogyra, Symphoricarpos, 



Tradescantia, and Elodea. According to these workers, the kinoplasm 



2^ Allied to this were conceptions involving archoplaam and ergastoplasm (see 

 Wilson, 1925, p. 723). 



3" Scarth (1927), Scarth and Lloyd (1927), Lloyd (1926), Lloyd and Scarth (1926). 



