120 PROBLEMS OF FERTILIZATION 



In the case of Nereis it could be seen that in aggluti- 

 nated masses the heads of many of the spermatozoa 

 are swollen into spherical form and have lost their nor- 

 mal strong refringibility; in such a case they are usually 

 motionless and, when not fused with one another, 

 appear to be glued to the slide or cover slip. 



De Meyer (191 1) observed that egg extracts of 

 Echinus, which contain certainly other substances than 

 the secretions of uninjured eggs, cause a strong swelling 

 of the head of the spermatozoon, including the nucleus, 

 and other transformations depending on the strength 

 of the extract and the duration of its action; the swell- 

 ing may increase the diameter as much as eight times. 

 The middle piece also swells and may divide. The 

 spermatozoa thus come to resemble small cells. Thus 

 he states that in sea-water extract of eggs the spermat- 

 ozoa undergo some of the changes which occur within 

 the normally fertilized tgg. 



Chemical and physical properties: The aggluti- 

 nating substance is colorless; it will not pass through a 

 Berkefeld filter, but passes readily through special hard- 

 ened filter paper; it is non-dialyzable; it is extremely 

 heat-resistant, being destroyed only slowly at the 

 boiling-point; it may be kept in sea-water for months, 

 though it slowly disintegrates. It is obviously colloidal 

 in its character, but Glaser (1914) has determined that 

 it does not give the usual protein tests : Millon's reagent 

 gave a white precipitate with no color changes on 

 boihng; the biuret test was negative; HNO3 gave no 

 ring, but a faint cloudiness; the xanthoproteic test 

 gave no precipitate, but the solution turned distinctly 

 yellow; the Adamkiewicz test was negative; Fehling 



