CHLAMYDOMONAS. 167 



upon the snow and ice of the Arctic regions, the snow-capped 

 peaks of the Alps and similar localities, that this little plant 

 prevails. The notice of botanists was first drawn to it by 

 Capt. Ross, 1819, on his return from Baffin's Bay, where it 

 was found extending for miles giving a red tinge to the 

 snow. Dr. Kane and other later explorers, report its fre- 

 quent occurrence. Judging by the descriptions given, the 

 arctic plant does not diifer essentially from the form found 

 on the high peaks of our Western chain of mountains. If 

 brought to a lower temperature and cultivated, it may be 

 questioned whether it would prove specifically distinct from 

 Chi. pluvialis. 



The plants as we receive them from the Rocky Mountains, 

 or from the Arctic regions, are in a quiescent state (resting 

 spores) which multiply rapidly by the simple process of 

 division of cells and would seem to belong to the genus Pro- 

 tococeus, but A. Braun and others who had more facilities to 

 observe the whole process of propagation, find they pass 

 through the various stages of a Chlamydococcus, forming 

 fugitive coenobia, macrogonidia and microgonidia furnished 

 with two cilia, etc. 



Plate CLIV, figs. 1, 2, simple cells ; figs. 3, 4, two cells 

 dividing into two, and into four parts. 



Genus 39, CHLAMYDOMONAS, Ehrb. 



Macrogonidia ovate or oblong-rounded, green, delicately gran- 

 ulated, involved in a rather narrow hyaline tegument, frontal 

 extremity very obtuse, or somewhat truncate with a contractile 

 vacuole, and two cilia ; posterior extremity with a large chloro- 

 phylose vesicle and with or without a red lateral spot. Micro- 

 gonidia arising from repeated division of the cytioplasm of the 

 macrogonidia ; oblong or ovate, numerous, pale green or yellow, 

 becoming brownish ; oospores globose, red or brownish ; con- 

 tents firm, colorless, hyaline. 



CHLAMYDOMONAS TINGENS, A. Br. 



Macrogonidia small, ovate or oval, light green without a 

 red pigment spot, membrane close. 



Diameter of cells, 7-8 yw ; length, 14-25 //. 

 Pools and ditches. 



Plate CLIV, figs. 5, 6, a variety of sizes of macrogonidia. 



I 

 CHLAMYDOMONAS PLUVIALE, Wolle. 



Macrogonidia spherical or nearly so ; bright-light green j 



