28 EXPERIMENT STATION RECOED. [Vol.36 



tween E. mexicana and T. dactyloidcs has been securerl, previous attempts hav- 

 ing always given negative results, though Euchla3na freely hybridizes with 

 maize. 



Of the four hybrid seeds planted April 8, 1913, only one germinated. The 

 seedling was found to resemble the male parent, E. mexicana, in practically 

 all discernible characters, and this resemblance continued throughout the life 

 of the plant. This plant is regarded as remarkable on account of the profound 

 morphological differences between the parents (one of which is moreover strictly 

 annual, the other perennial, requiring several years to mature), and the com- 

 pletely patroclinous characters of the hybrid. 



Patrogenesis, a form of inlieritauce with the characters of the female 

 parent completely excluded — a cross between two genera of grasses, Trip- 

 sacum and Euchlgena, G. N. Collins and J. H. Kempton {Jour. Heredity, 7 

 {1916), No. 3, pp. 106-118, figs. 8). — The one patroclinous hybrid reported above 

 was grown from a Tripsacum seed to maturity in the greenhouse, carefully 

 guarded, and self-pollinated, producing a quantity of seed. The first generation 

 plants were pollinated from a Florida Euchlgena and from two very late varieties 

 of tropical corn, all these pollinations being successful. A few seeds represent- 

 ing the results of each class of pollinations were planted in the gi'eeuhouse in 

 December, 1913, but gave only 7 plants, one of which failed as a result of 

 s-tructural abnormalities which are described. During the early stages, the 

 remaining 6 plants behaved much as did the first generation plant, but later 

 differences developed in some cases, which are described. Further plantings 

 (from the original lots of seed from the first generation plant), transplanted 

 to the open or made directly in open soil, developed no abnormalities. 



In 1915, experiments were conducted near San Diego, Cal., the long growing 

 season affording the first opportunity for the hybrid to mature undisturbed. 

 It is stated that the crosses between Tripsacum and Zea showed usually com- 

 plete resemblance to the female parent, and it is thought possible that Zea 

 pollen may have induced parthenogenesis in the Tripsacum plant. Studies to 

 lest this hypothesis have been instituted. 



In attempting to explain the fact that a cross between E. mexicana, male, and 

 T. dactyloides, female, has been carried over three generations without ex- 

 hibiting any characteristics of the female parent, it is thought that two hy- 

 potheses may be presented, namely, that the characters of the female parent 

 have been completely masked by those of the male, or that the male nucleus 

 developed in the ovary to the complete exclusion of the female, representing 

 in a way the counterpart of parthenogenesis. The observed facts and circum- 

 stances are tliought to exclude the first hypothesis. If the second alternative 

 be adopted, we are compelled, the authors hold, to look upon the results of the 

 cross as a special type of inheritance not previously recognized. No true hy- 

 bridization or conjugation between the two nuclei appears to have taken place. 

 The term patrogenesis is proposed as appropriate in such cases, also as serving 

 to place this phenomenon in proper contrast with parthenogenesis. This is 

 considered to have been rendered appropriate by the occurrence of what appears 

 to be true parthenogenesis in Tripsacum when pollinated with maize. 



Studies on the influence of temperature on the growth of the root of 

 Pisuni sativum, Isabella Leitch {Overs. K. Danske Vidensk. Selsk. Ford- 

 handh, No. 2 {1916), pp. 109-112). — Experiments are reported on the growth of 

 the roots of peas at various temperatures. The minimum temperature for 

 growth was found to be — 2°, the maximum 42.5° and the optinmm 29° C. 

 The maximum amount of growth for a very limited time occurred at 30.3°. 



The influence of temperature variations on the respiration of plants, 

 L. Blanc {Rev. Q6n. Bat., 28 {1916), No. 327. pp. 65-79).— The author has 



