400 ^^- Bateson. 



The "False Hybrids" of Millardet. 



M il lard et (77) recorded that in crosses between Strawberries 

 (Fragaria) he had seen cases where the offspring- came true to the 

 paternal type, and, on self-fertilisation, continued to reproduce that 

 type only. As far as I know these observations stand alone, and 

 until others like them are produced consideration may i)erhaps be 

 deferred. There are however a few examples of such an occurrence, 

 with the difference that it was the maternal type that was repro- 

 duced, which rest on perfectly sound evidence. 8uch cases are those 

 in which Trevor Clarke found that glabrous Matthiola $ X hoary $ 

 gave some glabrous offspring. Miss Saunders has confirmed this 

 result, and finds that such glabrous plants breed true (10, p. 45). 

 There are also the remarkable Orchid cases in which e. g.. Zygo- 

 petalum Mackayi $ was crossed with various other genera giving 

 purely maternal seedlings which have bred true (see Hurst (60) 

 p. 104). In these cases we are evidently concerned with some 

 distinct phenomenon of parthenogenesis — stimulated, apparently by 

 fertilisation — but as to the nuclear processes concerned, we know 

 nothing. 



Seeds remaining of purely maternal type after segregationc 



This is a very definite phenomenon the significance of wiiich is 

 still unknown. The example first discovered is tliat seen in F^ from 

 "indent" varieties of Pisum crossed with round-seeded varieties. In 

 Pisum there are three chief types of seed-sha])e, round, wrinkled, and 

 indent. Round and wrinkled Mendelize in the normal way, and 

 both types occur together in the same pods, just as green cotyledons 

 and yellow cotyledons do. Indent seeds occur only in varieties with 

 coloured flowers. Their surface is more or less irregular and indented. 

 Their starch-grains are indistinguishable from those of round peas, 

 and pollen from such plants put on to a wrinkled variety makes its 

 seeds round. F^ plants raised from such seeds have purple flowers 

 and coloured seed-skins, and their seeds are distinguishable as indent 

 seeds and wrinkled. But when a round seed is fertilised from an 

 indent plant the seed remains round, and when an indent is fertilised 

 by a round it remains indent. Whichever way the cross is made, 

 the F^ plant has exclusively indent seeds. 



To the eye at this stage there is no evidence of segregation. 

 Nevertheless segregation has been normal, as is proved by sowing 



