114 THE CELL 



temporarily paralysed in this manner united with ova when they 

 were brought to them, almost as quickly as fresh spermatozoa. 

 When they were kept for half an hour in the chloral solution, 

 a more marked paralysis was produced, which persisted for a 

 long time after the noxious agent had been removed. It was 

 not until some few minutes had elapsed that certain individual 

 isolated spermatozoa commenced to exhibit snake-like movements, 

 which gradually became more active. Even when they were 

 brought into the neighbourhood of ova, it was observed, that after 

 ten minutes none of these were fertilised, although several 

 spermatozoa had attached themselves to their surfaces, and had 

 bored their way in. But even in this case fructification and the 

 subsequent normal division of the eggs took place finally. 



Similarly, egg-cells become affected, as regards their irritability, 

 by a "2 to '5 per cent, solution of chloral hydrate or of some similar 

 drug ; this may be recognised by the abnormal manner in which, 

 after the seminal fluid has been added, the process of fertilisation 

 takes place. For whilst under ordinary circumstances only one 

 single spermatozoon penetrates into the ovum, with the result that 

 a firm yolk membrane is immediately formed, which prevents the 

 entrance of other spermatozoa, in Moralised eggs multiple fertilisa- 

 tion takes place. It has been proved that, according to the inten- 

 sity of the action of the chloral, that is to say, the stronger the 

 solution, and the longer it is allowed to act, the greater is the 

 number of spermatozoa which make their way into the ovum 

 before the formation of the yolk and membrane. Evidently the 

 effect of this chemical reagent is to lower the power of reaction 

 of the egg plasma, so that the stimulus which is produced by the 

 entrance of one spermatozoon is now no longer sufficient, but the 

 ovum must be stimulated by the entrance of two, three, or even 

 more spermatozoa, before it is sufficiently excited to form a mem- 

 brane. 



Finally, another example will show that the chemical processes 

 of 'the cell may also be hindered by anaesthetics. As is well known, 

 the yeast fungi (Saccliaromyces cerevisiw) produce alcoholic fer- 

 mentation in a solution of sugar, and during this process bubbles 

 of carbon dioxide rise through the fluid. When Claude Bernard 

 (IV. 1) added chloroform or ether to the solution of sugar, 

 before adding the yeast, no fermentation took place, although 

 in other respects the circumstances were favourable. But when 

 the yeast, after having been filtered out from the chloroform 



