376 



ANATOMY OF SPIRINA 



Method. Mount live nema in 

 sea water on large cover-glass; 

 cover with round one. Draw 

 off excess water till nema can 

 barely move. Seal with hot 

 wax. Use high immersion ob- 

 jective as condenser, its mate 

 as objective. Slight move- 

 ment of nema aids deciphering. 

 Stain ruptured nemas for fuller 

 examination. 



94.8 



2JO 



dU''M 



. .isc&zd cs 



X250 



Fig. 2. The male of S. parasitifera drawn from life. The tinting of drawing modi- 

 fied in accordance with study of stained specimens. Nearly all details shown were seen 

 in the living specimen. The front view of head, however, is from a decapitated speci- 

 men. In life the chromosomes have not been seen definitely enough to admit of accurate 

 counting. Most of the subsequent camera lucida drawings were obtained from fixed 

 and stained material. In nearly all cases the fixing and staining were done simulta- 

 neously by means of acetic acid methyl green. Just to the right are placed, in the 

 form of the decimal formula, the average measurements of specimens used. Material 

 collected at Woods Hole, Mass., U. S. A. 



The self-explanatory abbreviations are the same throughout the various figures, 

 and are of necessary Latin anatomical terms; thus, chrd lat, chorda lateralis, lateral 

 chord; qrt, quartet of spermatids; chrtd, chromatoids; spmtd, spermatid; alv ncl, alveoli 

 of nuclear space; micrsm, microsomes, of spermatid; 14, a 14-chromosome spermato- 

 gonial mitosis; mil, mitotic figure; grn, a cell of primary spermatidian tissue containing 

 four granules; grn 16, cell o? spermatidian tissue containing sixteen granules; locus 

 ncl alv, locus of the diminishing alveolated nuclear space; spmtd polyncl, polynucleate 

 spermatid in process of becoming a 64-celled tissue; textus spmtdi, spermatidian tissue. 



