114 PROCEEDINGS OP THE AMERICAN ACADEMY 



stain was hamiatoxylin, the specimen was partly decolorized in the 

 usual manner with very dilute hydrochloric acid in 70% alcohol ; if 

 the stain was some aniline, the surplus stain was simply washed out 

 in the 90% alcohol into which the specimen was always put next. 

 From 90% alcohol it was transferred to absolute alcohol, then allowed 

 to sink through alsolute alcohol into chloroform, then put into pure 

 chloroform. I then used a slight modification of the familiar chloro- 

 form method of imbedding in paraffine. I employed three mixtures of 

 soft paraffine and chloroform. No. 1 was a saturated solution ; No. 2 

 was two volumes of No. 1 plus one volume of chloroform ; No. 3 was 

 one volume of No. 1 plus two volumes of chloroform. The prepara- 

 tion was passed from pure chloroform into No. 3, into No. 2, and then 

 into No. 1. After the preparation was thoroughly saturated with 

 solution No. 1, the vial was uncorked and warmed until the chloroform 

 was all evaporated, or very nearly so. After this the specimen was 

 put into the soft paraffine bath, from this into the hard paraffine, and 

 then imbedded, sectioned in ribbons, and mounted with Schallibaum's 

 fixative and benzole balsam in the usual way. 



In staining I obtained the best results with hematoxylin. It brings 

 out the cell walls and nuclei well. Eosin shows the protoplasmic con- 

 tents of the cells better, but leaves the boundaries indistinct. I obtained 

 fair results with methyl-violet and safranin. 



It may be well before proceeding farther to examine the literature 

 that bas already appeared bearing on our subject. The first publica- 

 tion of interest in this connection is by Carl Nageli. In " Die Neuern 

 Algensystem," (Zurich, F. Schulthess, 1847, p. 246,) he treats of the 

 structure of Lomentaria kaliformis and of its method of growth. After 

 describing the thallus as hollow, jointed, and with whorled branches, 

 the joints being separated by cellular diaphragms, he goes on to say 

 that at the tip of the branch there is an apical cell (Scheitelzelle) which 

 he supposes to divide by oblique partitions. He does not seem to 

 have made this out very clearly, however. He says that the wall of 

 the thallus is two-layered, and he {wints out that in the younger portion 

 each of the outer cells abuts against a smaller inner cell. The outer 

 cells divide perpendicularly to the thallus, each into three or more, 

 and thus the cortex is formed; while the inner cells do not divide, but 

 become extended longitudinally and form the longitudinal filaments. 

 Nageli finds fifteen of these filaments in the adult frond. Their com- 

 ponent cells, are so elongated that it only takes two of them to reach 

 the length of a joint. Upon the inner side of each of these cells near 

 its middle there is a small globular or pear-shaped cell, or sometimes 



