558 FRANK R. LILLIE 



substances belong. It is, however, extremely improbable that 

 they possess a degree of chemical simplicity sufficient to allow of 

 volatilizing; it is more probable that they undergo slow chemical 

 disintegration at the temperature employed. The thermostabil- 

 ity of these sperm isoagglutinins is relatively very high, and this 

 perhaps makes it doubtful whether they can belong to the same 

 class of substances as the haem-agglutinins of vertebrate blood 

 sera. This matter must therefore remain undecided, and it 

 should be understood that the term agglutinin is used in the pres- 

 ent paper in a purely descriptive sense. ^ 



7. FERTILIZING POWER OF AGGLUTINATED SPERM 



The powerful effect of the egg-extract on spermatozoa of the 

 same species may be shown by a complete loss of motility as 

 we have already seen, and also by a corresponding loss or diminu- 

 tion of the fertilizing power. The following experiments illustrate 

 this : 



1. Arhacia. The egg-extract used was made by cutting up the ripe 

 ovaries in about three times their bulk of distilled water ; in half-an-hour 

 the water was filtered off and was then made isotonic with sea-water by 

 the addition of 42 parts of condensed sea-water to 58 of the egg-extract. 

 Five small watch crystals in a series contained (1) 8 drops of the egg-ex- 

 tract (2) 4 drops egg-extract, + 4 drops sea-water (3) 2 drops egg-extract, 

 + 6 drops sea-water, (4) 1 drop egg-extract, -f- 7 drops sea-water (5) 8 

 drops sea-water. To each of these 3 drops of opalescent sperm suspen- 

 sion was added; and after twelve minutes a drop of a suspension of 

 fresh eggs was added to each. We thus had the same quantity of eggs 

 in sperm suspensions of the same density, but in graded amounts of 

 egg-extract. The sperm suspensions were so dense that in the control 

 (no. 5) the jelly became packed with sperm, forming dense halos around 

 the eggs. In (4) a very few (about 1 per cent) had slight halos of sperm 

 in the outer layer of the jelly, but in (1), (2) and (3) the paralysis of the 

 sperm was so complete that they did not enter the jelly of the eggs at 

 all. Ninety-seven minutes later none of the eggs in (1), (2), (3) or (4) 

 had segmented; whereas at least 5 per cent of the control were now in the 

 two-celled stage. The lot of eggs was rather poor in this case, but fertili- 

 zation was confined entirely to the control. 



If the experiment be made in another way some recovery of the 

 spermatozoa from their state of paralysis may be observed. Thus: An 



* It should be borne in mind that but little is known concerning lysins or agglu- 

 tinins of invertebrates, 'it is perhaps not to be expected that they should exhibit 

 the same degree of thermolability as those of vertebrates. 



