1. A short description is given of an apparatus that aims at measuring the motility of sperm cells in an objective way.
2. In this method it is necessary to know the concentration on the slide for the determination of the value that indicates the motility. It was intended to measure this concentration with the same apparatus.
3. The measurement of the concentration met with some difficulties. A large scatter in the results was observed. This scattering is partly apparent in that it is caused by real differences in the concentrations which originate in the preparation of the slides. However, this apparent scatter hinders the determination of the exactness of the measurements. An estimate has been obtained, among other things, by means of a photographic experiment. There is some justification for expecting that a sufficient exactness can be obtained.
4. Notwithstanding the unexplained, and for the present still undoubtedly too large a scatter in the concentration measurements, a series of measurements of motility were made. The motility appears to be measurable by the apparatus, but there is still too great an error, so that the measurement does not yet come up to the visual method.
5. An effort to measure motility independent of the concentration on the slide (determination of the speed histogram) did not succeed because facilities were not available.