416 The Ohio Journal oj Science [Vol. XIX, No. 7, 



quality, but depends on the environment present during the 

 germination of the spore and the development of the embryo, 

 and it can be directly controlled in many cases by artificial 

 means." A statement of similar import has been included in 

 the several editions of the "Outlines" published independently 

 from time to time. In the fourth edition entitled "Laboratory 

 Outlines for General Botany," 1915, the more carefully worded 

 statement appears on page 23 as follows: " Maleness or female- 

 ness is not an hereditary character or factor, but a condition, 

 and often depends on the environment present during the ger- 

 mination of the spore or the development of the embryo." In 

 the meantime, after the knowledge of mutations and the 

 Medelian discoveries had become generally known, the problem 

 of sex has received renewed attention from numerous investi- 

 gators many of whom attempted to develop a general Mendelian 

 formula for sex, assuming the one sex to be homozygous and 

 the other heterozygous. There have, however, been many 

 whose experimental work has been in substantial agreement 

 with the undeniable conditions as presented by the Selaginella 

 type of plants. The remarkable work of O. Riddle on pigeons 

 has opened up a new line of attack on the problem connected 

 with the higher animals which may well be carefully considered 

 by experimental botanists. 



In conclusion the writer will present a number of paragraphs 

 from an article pubhshed in 1910, on "The Nature and Develop- 

 ment of Sex in Plants,"! in which the problem is discussed 

 from various angles. Among other conclusions expressed the 

 following seem appropriate here: 



"Sexuality expressed as maleness or femaleness, whether in 

 gametes, sexual organs, or individuals, is a condition and not 

 a character" (factor). 



"Sex may be determined sometime before reduction and 

 thus independently of any process going on during either a 

 vegetative or reduction karyokinesis; it may be determined 

 during the reduction division; it may be determined during 

 the fertilization stage; or finally, it may be determined after 

 vegetative growth has begun." 



"In some cases, when the sex is once determined it cannot 

 be changed in the vegetative body nor any vegetative spore or 

 propagative bud; in other cases, it may be changed in the 

 vegetative body after being developed as male or female." 



t Proc. Ohio Acad, of Sci. 5 : 321-350. 



