1895.] MICROSCOPICAL JOURNAL. 205 



To describe the discoliths : They are minute oval 

 bodies, one twenty-one hundredths of an inch in their 

 longest diameter. In their centre is a bright highly re- 

 fractive body called by Hseckel the "Centralkorn," which 

 is usually slightly, but frequently also markedly raised 

 above the surface as a knot when seen from the side. In 

 the flat area surrounding the central point, Haeckel's 

 "Markfeld," there are two or four slightly raised points 

 similar to the central one in it, but not nearly so much 

 differentiated. Round the " Markfeld " is the "mark 

 ring," which is a refractive ring of calcite, forming a 

 thick rounded rim to the little plate, and in the older 

 examples is slightly beaded. Hseckel then notices that this 

 surrounds itself with a granular ring, and finally with 

 another brightly illuminated outer ring. So that it is 

 an extremely small object with a series of concentric 

 rings on it, which are oval and marked with granula- 

 tions. 



What it is is doubtful, some calling it an animal and 

 some a vegetable. What it is chemically can be ascer- 

 tained approximately, being carbonate and phosphate of 

 lime with alumina and silicia. What it is geologically 

 is doubtful, being found in the chalk and living now. 

 That they are organic, there is no doubt, and belong to 

 that class of beings which are marked as merging on the 

 vegetable on one side and the animal on the other, in 

 fact Protista. 



John A. Ryder. — Perhaps the best memento we can furn- 

 ish to this naturalist who died March 26, 1895, is to print a de- 

 scription of his Microtome which will be found on another page. 

 Professor Ryder was born near London, Pa., in 1852. Since 

 1886 he has been professor of Embryology in the University of 

 Pa. He wrote extensively and was an opponent of Weisman- 

 nism. His early death was perhaps due to too intense appli- 

 cation to study. 



