98 CARNEGIE INSTITUTION OF WASHINGTON. 



ness to light. Dr. A. F. Blakeslee, of the Connecticut Agricultural 

 College, Storrs, has worked at this Station, as Research Associate, 

 on sex and mutations in molds, in part in collaboration with Dr. R. 

 A. Gortner. 



Of the more temporary appointments, Mr. H. D. Goodale resigned 

 in January to accept a position as research biologist in the Massa- 

 chusetts Agricultural Experiment Station, Department of Poultry 

 Husbandry. Dr. G. C. Bassett began in July, as a guest of the Labo- 

 ratory, his work on alcoholism and mental degeneracy in rats. 



To relieve the Director of details of accounts, supervision of work- 

 men, and purchase and care of supplies, the ofhce of Superintendent 

 was created and Mr. G. H. Clafiin began work in that capacity in 

 February 1913. 



REPORTS ON INVESTIGATIONS IN PROGRESS. 

 CHEMICAL BASIS AND HEREDITY OF SEX. 

 Sex in Molds, by A. F. Blakeslee. 

 The principal new work upon sex has been with molds, by Dr. 

 A. F. Blakeslee, and with Lychnis, by Dr. ShuU. Dr. Blakeslee's 

 efforts to discover which of the sexual races of mucors, provisionally 

 designated respectively as plus {+) and minus (— ), is actually male 

 and which female met with success. He had previously discovered 

 that among the white molds the majority of the species are dioecious, 

 with the male and female races indistinguishable from each other 

 except by a frequently greater vegetative luxuriance of the one race 

 provisionally called plus (+) over the other provisionally called 

 minus ( — ) . Since the gametes formed by these plus and minus races 

 are morphologically equivalent and the offspring are borne and nour- 

 ished equally by the two sexes, no means were at hand to decide 

 which of the two sexual races was actually to be considered male and 

 which female. However, certain hermaphrodite species were known 

 in which the gametes are regularly unequal. It was thought that if 

 one of the two sorts of races could be induced to show a sexual 

 reaction with the larger or female gamete of the hermaphrodite and 

 the other race with the smaller or male gamete it would be possible to 

 replace the provisional signs + and — by male ( cf ) and female ( 9 ) or 

 vice versa. Only two species have been found that show the sexual 

 reaction desired. The difficulties in technic involved are great, but 

 these have been satisfactorily overcome and it has been definitely 

 determined that the plus (+) race shows a sexual reaction with the 

 smaller or male ( cf ) gamete, while the minus ( — ) race shows a reaction 

 with the larger or female ( 9 ) gamete. The vegetatively more luxuri- 

 ant race, therefore, may be considered female and the less luxuriant 

 race male. Additional facts obtained by growing cultures in large 

 quantities seem to warrant formulating the general law that whenever 



