474 JEAN REDMAN OLIVER 



after parafPiii iinhoddiiij;-, sections 5 n were cut. Tliis was as tliin 

 as was found practical, and in most cases was found sufficient 

 for all purposes. After mounting on the slide the sections were 

 treated with a 2\ per cent solution of sodium thiosulphate, diluted 

 witli ten volumes of water, to remove all traces of iodine, as 

 reconunended by Heidenhain ('09). As for stains, though many 

 others were used, Heidenhain's iron hematoxylin was found by 

 far the most satisfactory, all the elements of the cells being 

 shown in a most favorable manner. The ordinary treatment was 

 used with a slightly longer period of mordantage, the sections 

 remaining in the iron bath for twelve hours at least, and then 

 from twelve to twenty-four hours in the stain. For contrast 

 stains erythrosin, eosin, congo red and orange G were mainly- 

 used, the first named giving the best results as it was less likely to 

 overstain and thus obscure delicate structures. This I found to 

 be a serious danger as a heavy stain is likely to cause delicate fila- 

 ments, such as are seen in the origin of the 'Schwanzmanschette' 

 or caudal tube, or the centrosomes even, to be overlooked. For 

 the study of the mature spermatozoa cover glass smear prepa- 

 i-ations were made from the epididymis, which has been pre- 

 served as a whole in 3 per cent formaldehyde. Further prepa- 

 I'ations were also made from new material secured by Mr. ( 'lark 

 in the sununer of 1012, and the whole development was verified 

 witli these. 



THE DIVISIONS OF SPP^RMIOGKNESIS 



In describing the process of the development of the adult 

 sperm from the spermatid I shall follow the plan first laid down 

 by Meves ('99) who separated the process into four main periods. 

 The first extends from the close of the division of the sperma- 

 tocytes of the Lid order to form the spermatids, up to the appear- 

 ance of the 'Schwanzmanschette,' or caudal tube; the second 

 extends from this appearance to its final disappearance; the third 

 period from this i)oint up to the migration of the adult sperm 

 into the lumen of the tubule; and the fourth period, that of the 

 so-called 'maturation,' consisting of minor changes in form and 

 density mainly, whicii take place in the epididymis. 



