DOUBTFUL PHENOMENA OF HEREDITY 387 



retarded by the action of various chemical substances, such as 

 chloral, quinine, and morphia; and we also know that the ova of 

 sea-urchins, if kept too long in the sea-water before being fer- 

 tilised, tend to lose their vital energy, and consequently many 

 spermatozoa, instead of a single one, are likely to enter each of 

 them. A similar result may follow from the effects of the above- 

 mentioned chemical reagents^ and in both cases an abnormal 

 development of the egg, such as a duplication of parts, may be 

 the consequence. 



It does not appear to me impossible that an intermixture of 

 alcohol with the blood of the parents may produce similar 

 effects on the ovum and sperm-cell. According to the relative 

 quantity of alcohol, either an exciting or a depressing influence 

 might be exerted, either of which would lead to abnormal de- 

 velopment. A depressing influence exerted on dot/i germ-cells 

 would certainly retard, or even quite prevent, the process of 

 fertilisation ; while if the egg-cell were a/one affected, super- 

 fertilisation (polyspermy) might result ; and the same might 

 occur by an excitation of the sperm-cells alone. The entrance 

 of several spermatozoa into the small human ovum, which con- 

 tains only a small amount of yolk, might produce an abnormal 

 development just as much as in the case of the eggs of the star- 

 fish or sea-urchin. A high degree of excitation in both germ- 

 cells might, on the other hand, cause the complicated processes 

 of the increase of the germ-plasm in the ovum and the subse- 

 quent conjugation of the two germ-plasms to take place in an 

 inexact manner, owing to their being passed through too quickly, 

 and would then produce an irregular development. 



JVew predispositions can certainly never arise owing to such 

 deviations from the normal course of development, and therefore 

 a modification of the process of heredity itself is out of the 

 question. It is, however, conceivable that more or less con- 

 siderable abnormalities may affect the course of development, 

 and either cause the death of the embryo, or else produce more 

 or less marked deformities. The question as to whether such 

 deformities really result in consequence of the dnmken con- 

 dition of the parents can only be decided by observation. 



3. The Supposed Transmission of Diseases 



There is no doubt that some diseases are passed on from one 

 generation to another. All such cases are not, however, con- 



