LATENT TRANSMISSION. 207 



dividuals of which live isolated and possess an eye of the form 

 of a horse-shoe, produce in a non-sexual manner (by the 

 formation of buds) a completely different and smaller gene- 

 ration. The individuals of this second smaller generation 

 live united in chains and possess a cone-shaped eye. 

 Every individual of such a chain produces, in a sexual man- 

 ner (hermaphrodite) again, a non-sexual solitary form of the 

 first and larger generation.. Among the Salpse, therefore, it 

 is always the first, third, and fifth generation, and in like 

 manner the second, fourth, and sixth generations, that are 

 entirely like one another. However, it is not always only 

 •one, but in other cases a number of generations, which are 

 thus leapt over; so that the first generation resembles the 

 fourth and seventh, the second resembles the fifth and 

 eighth, the third resembles the sixth and ninth, and so on. 

 Three different generations alternate with one another ; for 

 example, among the neat little sea-hiioys (Doliolum), small 

 tunicates closely related to the Salp^. In this case it is 

 A = D =G, further, B == E = H, and C = F = I. Among 

 the plant-lice (Aphides), each sexual generation is followed 

 by a succession of from eight to ten or twelve non-sexual 

 generations, which are like one another, but differ from 

 the sexual generations. Then, again, a sexual generation 

 reappears like the one long before vanished. 



If we further follow this remarkable law of latent or in- 

 terrupted inheritance, and take into consideration all the 

 phenomena appertaining to it, we may comprise under it 

 also the well-known phenomena of reversion. By the term 

 " reversion " or " atavism " we understand the remarkable 

 fact known to all breeders of animals, that occasionally 

 single and individual animals assume a form which has not 



