340 f'roci'cdiiKjs of the Ohio State Academy of Science 



Ophryotrocha puerilis is usually unisexual but occasionally her- 

 maphrodite. Braem halved a female with ripe eggs. The head 

 portion with 13 segments was isolated and in three weeks it 

 had regenerated 7 segments. The ova had disappeared from 

 the gonads and a functional spermary had developed which was 

 producing spermatozoa. Braem thinks that the very young in- 

 dififerent germ cells had developed as male cells in consequence 

 of the amputation. There was no trace of hermaphroditism. 

 It is certain, therefore, that the gonads changed from an egg- 

 producing to a sperm-producing tissue. 



In dioecious ])lants also where some of the imperfectly car- 

 pellate individuals have bisporangiate flowers, poor nutrition, in- 

 duced by various causes, lessens the proportion of bisporangiate 

 flowers. Correns found that in Satureia the production of a 

 greater or less number of carpellate or bisporangiate flowers is 

 dependent upon nutrition in its widest sense, notwithstanding 

 that he believes sex is determined in Mendelian ratio. 



All the known facts clearly indicate that various external 

 and internal conditions, are able to influence the expression of 

 hereditary characters, although they may not afl^ect the trans- 

 mission of characters. This has lately been emphasized by O. 

 F. Cook. 



Differences of heat, light, food, chemicals, and internal se- 

 cretions are known to induce changes in the expression of char- 

 acters. The necessary presence of the thyroid gland in man, 

 the presence of the spermaries in the higher animals, the in- 

 fluence of gall producing organisms on the higher plants, the 

 efl:"ect of scions on the character of the roots on which they are 

 grafted, all show how expression of hereditary characters can 

 be changed in the individual. A remarkable fact in support of 

 the proposition that the morphological expression of sexuality 

 is the result of a condition is presented by the known cases of 

 sterile female birds which sometimes take on the male plumage. 

 All these phenomena appear to indicate that sexual characters 

 are a common inheritance, there being no female hereditary 

 characters as such nor male characters, but general characters 



