358 JULIA ELEANOR MOODY 



as though in process of division (figs. 11 and 15); but since 

 these bodies occur so rarely, they cannot be reasonably considered 

 permanent cell structures. The macronucleus, extending length- 

 wise of the cell, is a greatly elongated, rod-shaped body, circular 

 in section, measuring from 4/^ to 8/x in diameter. It is coiled, 

 twisted and folded upon itself, often attaining a length two or 

 three times that of the body (figs. 1, 4 and 5). Although the 

 typical nucleus is long and intricately coiled, a few exceptions 

 were found, two of which are shown in figures 9 and 16. The 

 former might be interpreted as indicative of beginning division; 

 this however is not the case, since in the many division stages 

 studied, the nucleus could always be traced as a continuous 

 band from the anterior to the posterior cell. The macronucleus 

 is bounded by a very delicate membrane which may be readily 

 seen in total preparations which have been compressed by the 

 cover-glass. Here the macronucleus, free from the surrounding 

 protoplasm, retains its definite outline. The chromatin of the 

 macronucleus consists of a mass of minute granules, which take 

 an intense color in staining with iron-haemotoxylin. Surround- 

 ing the chromatin masses is a faintly staining substance which 

 in section appears somewhat more opaque than the protoplasm 

 of the cell. The granules in the late stages of division are ex- 

 ceedingly fine (figs. 21 and 22). In earlier stages, where an 

 elongation of the cell body has taken place, but as yet no con- 

 striction can be seen, the chromatin appears as deeply stained 

 fine threads which would seem to indicate a division of the larger 

 chromatin granules (figs. 19 and 20). Although it is generally 

 thought that the possession of the two types of nuclei is char- 

 acteristic of the ciliates, the present observations give no evidence 

 of this differentiation in Spathidium. 



4- Reproduction 



« 



Spathidium multiplies by simple fission, the rate of division^ 

 according to Maupas, being one division in twenty-four hours- 

 The" cultivation of Spathidium during two hundred and eighteen 

 generations, showed considerable variation in the division rate. 

 During one ten-day period, the average daily rate of division 



