ox CRISTISPIEA VEXEKIS NOV. SPEC. 519 



1, PI. 20. This organism is from a moist film preparation of 

 a crystalline style wliicli was so treated. The whole organism 

 (fig. 1) shows a protoplasmic structure consisting of a single 

 row of chambers or alveoli. The walls of these chambers are 

 stained a deep blue, their contents a uniform pale blue. The 

 relative dimensions of these chambers are not always constant; 

 they may vary not only in different organisms, but at different 

 points in the same organism — being sometimes square, some- 

 times oblong (cf. figs. 7, 8, etc.). The alveolar walls 

 separating adjacent chambers from one another appear as 

 transverse septa in optical section (see figs. 1, 2, etc.). At 

 the point where the transverse septum joins the wall of the 

 cell a dark purple granule can be seen. The whole organism 

 thus appears to contain a series of paired purple granules, 

 united by blue transverse lines — representing the alveolar 

 walls (fig. 1). This appearance is always presented by indi- 

 viduals treated in the manner described. If the exposure to 

 osmic vapour has been limited to about thirty seconds, and no 

 overstaining has taken place, then the appeai-ances are con- 

 stantly encountered. The difference in size observable in the 

 purple granules should be noted — also the fact that they 

 always lie at the edges of the organism, and never centrally 

 (figs. 1,7). 



If the osmic vapour be allo\ved to act for a longer period 

 of time — i. e. for several minutes — then the organisms present 

 a different appearance after Giemsa staining. The granules 

 appear much smaller, and are stained a deep blue (figs. 2, 8). 

 The chambers are easily visible, but the granules have 

 dwindled to tiny dark blue points. In some cases they 

 cannot be distinguished with precision at all levels in the 

 body (cf . fig. 6). 



Organisms which have been dried previous to fixation, fixed 

 in absolute alcohol, and then stained by Giemsa's method in 

 the usual way, often present appearances which are quite 

 different from those seen in osmic-fixed organisms. They 

 show, in fact, all the remarkable " chromatin" configurations 

 which have been described by Perrin and others. The 



