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512 University of California Publications in Zoology [VOL. 11 



reasons: (1) The male sex cells are large; (2) the animal is 

 fairly common in this vicinity and may be obtained throughout 

 the entire year; and (3) the seriation of stages within the testes 

 is easily followed because all phases are frequently found in a 

 single testis, beginning at the anterior end with lobules of sper- 

 matogonia and passing posteriorly to a region occupied by mature 

 spermatozoa. Moreover, the cells in any particular lobule appear 

 to have reached approximately the same stage in differentiation. 



The material used for this research was obtained within a 

 radius of five miles from Berkeley, with the exception of a few 

 specimens from Twin Peaks, San Francisco, and much of it was 

 secured upon the campus of the University of California. The 

 salamanders may readily be found under stones and logs or in 

 crevices of the rocks. They have also been taken in burrows 

 at least a foot below the surface of the soil, but in all such cases 

 observed the burrow opened beneath a rock. It is difficult to 

 find them during the dry season, as they seek the deeper, moist 

 levels. According to the investigations of Hitter and Miller 

 (1899), they breed in June and July. Although no specimens 

 were collected during June, July, and September, material was 

 obtained during every other month. 



A number of fixing fluids and staining processes were tried 

 with varying success. Bouin's, Zenker's, and Flemming's fluids 

 proved most valuable and were extensively employed. Gilson's 

 fluid seemed to damage the cells of the outer cysts; otherwise, 

 some very good late prophases were obtained by its use. The 

 testes were embedded in paraffin and sectioned longitudinally 

 in order to show the seriation to the best advantage. The sections, 

 cut from six to twelve micra in thickness, were mounted on slides 

 in the usual way. 



With Bouin's and Zenker's fluids three stains were tried: 

 iron-alum-haematoxylin with orange G and acid fuchsin as coun- 

 terstains; safranin followed by gentian violet; and phospho- 

 tungstic acid haematoxylin. The last seems to be the best for 

 general purposes, as it stains the growing spermatocyte beauti- 

 fully without overstaining the mitotic figures. It differentiates 

 the structures of the cell very clearly, staining the chromosomes 

 deep blue and the spindles reddish. Many equatorial plates can 



