438 Mr Gregory, Some observations upon 



Summary. 



The production of one or other of the two forms of gamete by 

 the gametophyte of the Vascular Cryptogams and higher plants 

 is to be distinguished from the separation of the sexes observed in 

 animals, in the sporophyte of higher plants, and probably from 

 that in the Thallophyta. 



The form of gamete produced by the gametophyte may be 

 influenced, within limits, during the independent existence of the 

 gametophyte by the environment (Homosporous Plants); or it 

 may be determined under the influence of the parent sporophyte 

 (Heterosporous Plants). 



The form of gamete produced by any gametophyte is. in- 

 dependent of the sex-character transmitted through that gameto- 

 phyte to the sporophyte of the next generation. 



All plants which have a primitive hermaphrodite sporophyte 

 produce gametes undifferentiated in respect of the segregation of 

 the sex-characters. 



I should like to take this opportunity of acknowledging my 

 indebtedness to Mr Bateson for the many suggestions and advice 

 he has given me throughout this work. 



BIBLIOGRAPHY. 



Bateson, 1894. "Materials for the Study of Variation." London, 



Macmillan, 1894. 

 Bateson & Saunders, 1902. "Experimental Studies in the Physiology 



of Heredity." Reports to the Evolution Committee of Royal 



Society, I. 

 Bauke, 1878. " Entwickelungsgeschiehte des Prothalliums bei den 



Cyatheaceae verglichen mit derselben bei anderen Farnkrautern." 



Rringsheim's Jahrb. x., p. 29. 



— 1878. "Beitrage zur Keimungsgeschichte der Schizeaceae." 

 Pringsheim's Jahrb. xi., p. 603. 



Blochmann, 1888. " Ueber die Bichtungskorper bei unbefruchtet 

 sich entwickelnden Insekteneiern." Verh. naturh. med. Ver. 

 Heidelberg, N. F., iv. 1892, p. 239. 



— 1889. " Tiber die Zahl der Bichtungskorper bei befruchteten und 

 unbefruchteten Bieneneiern." Morph. Jahrb., Bd. xv. H. 1, p. 85. 



Boveri, 1902. "Mehrpolige Mitose als Mittel zur Analyse des 

 Zellkerns." Verh. d. Rhys. Med. Ges. zu Wilrzburg, xxxv. 



— 1904. "Ergebnisse iiber die Konstitution der chromatischen 

 Substanz des Zellkerns." Jena, Gustav Fischer, 1904. 



