224 MR. NEWPORT ON THE IMPREGNATION OF 



suspension rather than in chemical combination. When placed on a single filter, the 

 solution passed through with extreme difficulty and slowness. When a microscopic 

 drop of the fluid so passed was examined with a power of three hundred diameters, 

 it was found to contain a large quantity of granules suspended in clear fluid. When 

 made to pass, but with still greater difficulty, through a second filter, it still contained 

 a quantity of minute granules, but each less than one-half' the diameter of the sperma- 

 tozoon. It is possible, therefore, that some extremely minute granules may penetrate 

 into the texture of the envelope, formed as it is of aggregations of cells ; but it seems 

 to be very improbable that any of the larger-sized objects, such as the spermatozoa, 

 can enter : and it is even much more improbable, that if the chief colour of the ova in 

 my experiments was due, as I believe, to granules of carmine on the surface, and not 

 in the interior of the ova, that in MM. PREVOST and DUMAS' experiments with frog's 

 blood, the ova should have become reddened by the admission of particles of this 

 into their interior, since it need scarcely be mentioned that the colour of the blood is 

 due only to the particles suspended in it ; and MM. PREVOST and DUMAS remark, 

 that they were not able to detect any blood-globules on the surface. To what else, 

 then, than to these, or to their broken-down particles, could the reddened colour 

 of the ova in their experiments be due ? 



The conclusion, then, to which I am led by these experiments is, that although the 

 envelopes of the egg imbibe coloured fluid, they do so less easily than when the fluid 

 is not coloured, unless it is in chemical combination ; and although atoms of solid 

 matter, very much smaller than the spermatozoa, may possibly be carried by infiltra- 

 tion into the texture of the egg-envelope by the act of endosmose during its expansion, 

 it appears to be extremely unlikely that the large bodies of the spermatozoa are so 

 carried in ; an improbability which is raised almost to a certainty by the fact that the 

 spermatozoa are not seen attached to the egg with a centripetal direction of the axis 

 of their bodies, but are constantly applied laterally to, or are entangled amongst the 

 loose tissue of the surface, extended at length or partially folded on themselves. 



6. AGENCY OF SPERMATOZOA AS AFFECTED BY CHEMICAL MEDIA. 



The experiments with carmine having led to an unexpected result in the impedi- 

 ment which this medium offers to the impregnation of the ovum when immersed in it 

 before contact with the spermatozoa, I was desirous of ascertaining what effect would 

 be produced on the ovurn by the destruction of the spermatozoa by chemical means, 

 immediately after they had been applied to it. Mr. GULLIVER* long ago showed that 

 the spermatozoa of different animals are variously affected by different chemical tests ; 

 and Dr. FRERICHS-^, more recently, has found that a solution of caustic potass has 

 the property of entirely dissolving and destroying them. This material, therefore, 

 seemed to be peculiarly fitted for the object in view. But before any experiment, in 



* Proceedings of the Zoological Society, part 10. p. 101. July 26, 1842. 



t In Cyclopaedia of Anatomy and Physiology, Article " Semen," p. 506, January 1849. 



