AND ON THE DIRECT AGENCY OF THE SPERMATOZOON. 283 



The object which I had in view was to endeavour to learn what proportion of the 

 carbonates of potass and soda may be present in a given quantity of water without 

 destroying the fertility of the egg. The first trials with potass were made with eggs 

 which had already been fecundated, and were undergoing segmentation. It was 

 then found that when fecundated eggs, arrived at the second stage of segmentation 

 of the yelk, were immersed in a solution, composed of twenty grains of the fused 

 carbonate of potass to one ounce of water, the yelks became shrivelled, and decom- 

 position was commenced within three minutes after immersion ; thus proving that 

 even when the envelopes of the egg are almost fully expanded, and, consequently, 

 when their endosmic action may be expected to have become greatly diminished, 

 that endosmosis may still be going on with much energy. It is right to mention, 

 however, that in this and the following experiments, the endosmic action may have 

 been, and probably was, increased by the removal of the eggs which already retained 

 water in their tissues to the more dense fluid solution ; but as the experiments are 

 comparative, the circumstance is not of much importance. 



On the contrary, when some eggs were immersed in a solution of one-fourth of a 

 grain of the salt to one ounce of water, and the potass in admixture with the water 

 was thus reduced to ywo tn part of the whole, development went on more quickly 

 than in other eggs of the same brood, impregnated at the same time, but which were 

 placed in pure water apparently through the potass occasioning a slight increase of 

 temperature. 



These results appear to be explicable only on the assumption that the weak potass 

 solution acts as a chemical stimulus, perhaps both to the egg and to the sperma- 

 tozoon, at the time of fecundation, a view which derives some support, in so far as 

 refers to the spermatozoon, from direct observation with the microscope. Thus, 

 when a drop of the two-grain solution of potass is applied to spermatozoa on a plate 

 of glass, covered with talc, beneath the microscope, the movements of these bodies 

 are not instantly arrested, as by the stronger solutions, but gradually become slower 

 and slower, until they entirely cease, apparently, in proportion as their substance 

 becomes affected by the potass. The one-grain solution very much accelerates the 

 movements of these bodies during the first few seconds ; but in a few seconds longer 

 these also become diminished like the preceding. But the effect of the half-grain 

 solution, although exciting the spermatic bodies to activity as soon as it comes into 

 contact with them, continues its effect for a much longer time without acting 

 injuriously upon their substance; and it is not until after the lapse of many minutes 

 that the intensity of the motion excited by it is observed to be diminished, and the 

 movement to slacken and afterwards gradually cease. 



With regard to the carbonates of soda, I may state that the general effect of these 

 on the impregnated and on the unimpregnated egg are very similar to those of 

 potass, but are far less prejudicial, or marked, so that it is unnecessary to detail the 

 experiments. 



MDCCCLHI. 2 P 



