STUDIES ON SPATHIDIUM SPATHULA 191 



green, nigrosin, dahlia, Bensley's mitochrondria, gentian violet, 

 Loeffler's, Mallory's triple stain, picro carmine, Delafield's haema- 

 toxylin, and Heidenhain's iron haematoxylin. 



MORPHOLOGY OF SPATHIDIUM 



The general structure of Spathidium as described by Moody 

 is corroborated by the study of the animals of our pedigree 

 cultures. The flask-shaped form of a typical vegetative in- 

 dividual is well illustrated in figure 9. But specimens im- 

 mediately before and after division, encystment, and conjugation, 

 as well as when starved and after a heavy meal, exhibit very 

 marked changes from the typical condition. In addition to the 

 diversities in the relative proportions of the various parts of the 

 cell under these varying circumstances the contortions of the 

 organism, when it becomes entangled in zoogloeal debris, etc., 

 augment the protean picture which it presents, though we have 

 never seen a specimen 'double its length' as recorded by Moody. 

 But such a succession of forms is apparent that many might be — 

 indeed, some have been — designated as distinct species .(Cf. figs. 

 9, 10, 13, 14, 19, and 20). As a matter of fact, the attempt to 

 determine the specificity of widely different specimens in a wild 

 culture led to the discovery of the peculiar advantages afforded 

 by Spathidium for experimental purposes. 



Cilia. The ciliation of the specimens in our cultures agrees 

 with Moody's description, there being about sixteen longitudinal 

 rows of cilia evenly distributed over the cell. However, each 

 of these bands is in turn made up of two closely opposed rows 

 of cilia. It has been impossible to demonstrate this composite 

 character of the bands in living specimens, but sections clearly 

 reveal a double row of basal granules in each band. At the 

 edge of the truncated anterior end there are two rows of some- 

 what longer and stouter cilia, the stronger beat of which is par- 

 tially responsible for the characteristic gyrations of the anterior 

 end as the organism swims forward revolving on its long axis. 



The cytostome consists of a long narrow depression extending 

 almost, if not quite, the whole length of the truncated end nearly 

 at right angles with the long axis of the cell. At the bottom of 



THE JOURNAL OF EXPEIUMENTAL ZOOLOGY, VOL. 35, NO. 2. 



